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1977 The effects of metabolic acidosis on glucose metabolism Alan Dennis Beckles Yale University
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https://archive.org/details/effectsofmetabolOObeck THE EFFECTS OF METABOLIC ACIDOSIS ON GLUCOSE METABOLISM
Alan Dennis Beckles
B.S. Columbia University, 1971
M.S. Columbia University, 1973
Presented to
The Faculty of Yale University
School of Medicine
In Candidacy for the Degree of
Doctor of Medicine
1977
The author wishes to thank Mrs. Lois Mishwiec for her patience, good humor and technical assistance, Mr. Ralph Jacob for his technical assistance and Ms. Coreen Bentham for tolerating constantly changing deadlines.
TABLE OF CONTENTS
I. INTRODUCTION
II. METHODS
A) Subjects
B) Hyperglycemic Clamp
C) Euglycemic Clamp
D) Calculations
E) Analytical Procedures
III. RESULTS
A) Hyperglycemic Clamp
B) Euglycemic Clamp
IV. DISCUSSION
V. SUMMARY
VI. REFERENCES
VII. LEGENDS TO FIGURES
VIII. FIGURES
IX. TABLES
INTRODUCTION
Impaired carbohydrate tolerance is a common accompaniment of diabetic ketoacidosis (1) and chronic renal failure (2). Common to both these states is the presence of metabolic acidosis. Although several previous animal
(3-5) and in vitro (6-8) studies have suggested that acidosis per se may result in an impairment of glucose metabolism, such an effect has not been well studied in man and the mechanism(s) by which acidosis impairs glucose metabolism have not been defined.
Haldane et.al. (9) were the first to examine the effect of metabolic acidosis on glucose metabolism in man. Following the injestion of ammonium chloride they found an impairment of glucose tolerance which persisted for some time following the return of blood pH to normal. Walker et.al. (6) noted decreased sensitivity to exogenously administered insulin in six diabetics with ketoacidosis (blood pH <7.20) and improvement in insulin sensitivity following correction of the acidosis. However, these authors could not exclude other changes in the diabetic state as responsible for the improvement in insulin sensitivity. In the only other study in man, Baird
(10) was unable to demonstrate any adverse effect of ammonium chloride induced acidosis on the intravenous glucose tolerance test. However, all of his subjects were treated with quinalbarbitone prior to study and this could have obscured any differences between the control and ammonium chloride treated groups.
Mackler et.al. examined the effect of ammonium chloride induced metabolic acidosis (mean blood pH and serum bicarbonate concentration = 7.06 and 6 mEq/L) in dogs (3-5). They found a consistent increase in fasting glucose concentra¬ tion, a blunted response to exogenous insulin, and impairment in the intra¬ venous glucose tolerance test. They also observed a failure of the normal decline in serum potassium and phosphate concentration (11-14) in response to both insulin and glucose, again suggesting impaired sensitivity to the action of insulin. However, the interpretation of the above studies is obscured by the fact that the dogs were also fasted over the three days during which the metabolic acidosis was induced. Thus, it is difficult to differentiate an effect of acidosis versus fasting on the decline in glucose tolerance. In the only other study performed in dogs, Deuel and Gulick were unable to demonstrate an effect of ammonium chloride-induced acidosis on carbohydrate tolerance (15). In vitro studies employed the rat epididymal fat pad (6), the rat hemidiaphragm (6,8), and circulating erythrocytes and leukocytes (5,7) have also suggested that acidosis inhibitsglucose uptake and oxidation.
To examine the effect of metabolic acidosis on glucose metabolism and to define the relative contributions of impaired insulin resistance, imparied beta-cell secretion of insulin, and augmented hepatic qlucose oroduction to the carbohydrate intolerance, we studied 12 subjects with the glucose clamp technique before and after the induction of chronic metabolic with ammonium chloride.
METHODS
A. Subjects: (Table I). Twelve healthy volunteers ranging in age from 22 to 31 were studied. They were evenly divided between males and females and all were within 20% of their ideal body weight. The middle of the weight range for subjects of medium frame from the 1959 Metropolitan
Life Insurance Company table for desirable weight was used to determine ideal body weiqht. All subjects were consuming a weight maintainina diet containing at least 200 gms of carbohydrate per day for 3 days prior to study. Other than subjec
M.K., M.D. and M.S., who were on oral contraceptives, subjects consumed no other medications for at least two weeks prior to study. There was no family history of diabetes. A total of 24 studies were performed on the 12 subjects. All subjects were studied at 8 a.m. following a twelve hour overnight fast. Following the initial study each subject received ammonium chloride in a dose of either 0.1 or 0.15 gm/kg of body weight per day for three days and the study was repeated on the morning of the fourth day. Each subject thereby served as his own control. The ammonium chloride was administered in divided doses every 6 hours with the last dose being given at 11 p.m. on the evening prior to study. Although two subjects complained of mild abnormal discomfort, there was no vomiting and all continued on the diet as stated above.
Prior to each study a polyethylene catheter was inserted into an anticubital vein under local xylocaine anesthesia for administration of all test substances. A second catheter was inserted into a hand vein for blood sampling. The hand was then inserted into a heated chamber in which the air temperature was maintained at 70±2 degrees centigrade. This was done to insure arteriolization of venous blood (16).
B. Hyperglycemic Clamp: After a control period of at least thirty minutes a priming infusion of glucose designed to rapidly raise the blood glucose concentration to 125 gm/dl above the fasting level was administered in a logarithmically falling manner over 15 minutes. Arteriolized venous blood was sampled every two minutes for the first ten minutes to quantitate the early releasable insulin peak. Thereafter, blood samples were drawn every five minutes for 110 minutes. The plasma glucose concentration was rapidly determined (analytical delay was less than two minutes) on each sample and the infusion rate of a 20% glucose solution was adjusted to maintain the blood glucose concentration constant at 125 mg/dl above the basal level. The formula for the servo-correction is based upon the negative feedback principle. Thus, if the actual plasma glucose concentration is greater than the goal, the glucose infusion rate is decreased and vice-versa. Of pertinence to this paper is the fact that the actual plasma glucose concentration was maintained within narrow limits of the specified goal
(see Results). Under these steady-state conditions of constant hyperglycemia the amount of glucose infused (mg/kg of body weight/min) minus urinary losses
(mg/kg of body weight/min) is a measure of the glucose metabolized, M.
Although the clamp method does essentially eliminate variance from subject to subject in blood glucose concentration, the plasma insulin levels are not the same in all subjects. In the euglycemic clamp (see below), insulin levels vary only as a function of its metabolic clearance rate (MCR). In the hyperglycemic clamp insulin levels vary not only as a function of MCR, but also on a function of the sensitivity of the beta cell to hyperglycemia.
The fact that insulin levels vary makes it essential to correct the value for M in some manner to take this variance into account. The simplest technique is to compute the ratio of M to the plasma insulin level, I, that is, to compute M/I. The underlying mathematical assumptions of such a computation are that M is linearly related to I and that there is no intercept of M on I. If either of these two assumptions is incorrect, then a more complex formulation would be required. For example, computation of an M/log I
might be justified. We have chosen to correct for the insulin concentration by the simplest possible technique, M/I. The mean insulin concentration in the 24 euglycemic and hyperglycemic clamp studies is 104 uU/ml (Tables 2 and 3) with a standard deviation of ±32. Within these reasonably narrow limits it is doubtful whether more complex formulations would significantly change the conclusions presented.
C. Euglycemic Clamp: A prime plus continuous infusion of crystalline
porcine insulin (Eli Lilly Co., Indianapolis, In.) was administered to obtain constant hyperinsulinemia (17). The primary dose was administered in a
logarithmically falling manner over ten minutes at which time the continuous
insulin infusion was begun. The total amount of insulin infused during the
priming period was twice that infused during subsequent ten minute intervals. p The continuous infusion (40 mU/m surface area per min) was maintained for
110 minutes. In order to prevent insulin adsorption to glassware and to
the plastic infusion apparatus, infusates were prepared with the addition of
2 ml of the subject's whole blood per 50 ml of infusate. Hypoglycemia with
its attendant counter-regulatory responses was prevented by the glucose clamp
technique (see under hyperglycemic clamp) which was used to maintain each
subject at his own basal blood glucose concentration during insulin administration. The initial glucose infusion rate was 2.0 mg/kg body weight/ min and was started four minutes after the insulin infusion was begun. At
ten minutes the glucose infusion was increased to 3.0 mg/kg/min; these doses were empirically determined. The first servo-correction was made at 14 minutes. Under the condition of constant euglycemia all of the glucose
infused (M) is metabolized and is thus a measure of the body's sensitivity
to insulin. During the euglycemic clamp the effect of insulin on hepatic
glucose production was examined with tritiated glucose labeled in the 3
position ([%]glucose). For 3 hours prior to beginning the insulin infusion,
each subject's glucose pool was labeled by a primed continuous infusion of
[^T] glucose. The labeled glucose was administered as an initial intravenous
priming dose followed immediately by a continuous intravenous infusion at a
rate of about 0.25 uCi/min. Plasma samples for determination of glucose
specific activity were taken at 30 minute intervals for the first two hours
and at 15 minute intervals for the subsequent hour. A steady state plateau glucose specific acticity was achieved in all subjects during the third hour of [3t] glucose infusion and this plateau value was used to calculate basal hepatic glucose production. After 3 hours of continuous [^T] glucose infusion, the euglycemic clamp was begun as previously described and the continuous infusion of [~T] glucose was continued at the same rate. During the clamp study plasma samples for glucose specific activity were drawn every 15 minutes. Three control samples for amino acids and glucagon were obtained prior to beginning both the euglycemic and heperglycemic clamp studies; subsequent samples were drawn at 15-30 minute intervals.
D. Calculations: Hyperglycemic Clamp: The fasting plasma insulin concentration, the early (0-10 minute), late (20-120 min), and total plasma insulin (I) responses, the amount of glucose metabolized (20-120 minute time period) and the M/I ratio (a measure of tissue sensitivity to insulin) were compared before and after NH^l loading. The basal glucagon and amino acid levels as well as the change in plasma glucagon and amino acid concentrations following glucose were also compared before and after NH4C1 loading.
Euglycemic Clamp: Tissue sensitivity to insulin (M/I ratio during time
= 20-120 minutes) and the metabolic clearance rate (MCR) of insulin were compared before and after ammonium chloride loading. The MCR of insulin was calculated by dividing the insulin infusion rate by the steady state plasma insulin concentration during the 40-120 minute time period minus the basal insulin concentration. Plasma glucagon and amino acid concentrations were analyzed as described above for the hyperglycemic clamp. Basal hepatic glucose production before and after ammonium chloride loading was determined 3 by dividing the [ T] glucose infusion rate (counts/min) by the steady state plateau of [ T] glucose specific activity during the last hour of the control period. Following insulin-glucose administration (euglycemic clamp) a non¬ steady state condition in glucose specific activity exists and hepatic glucose production was approximately using the Steele equations (equations 4A and
5A, reference #18) average values for the rates of glucose turnover for the intervals between two conservative sampling times.
All data are presented as the mean - SEM. Statistical significance between the difference of two means was calculated by paired T-test analysis.
E. Analytical Procedures: Plasma glucose analyses were performed in duplicate on arterized venous samples using the glucose oxidase method
(Glucostat, Beckman Instruments Corp., Fullerton, Ca. 92634). Insulin was determined by radioimmunoassay with talc to separate bound from free insulin
(19). Plasma glucagon was analyzed by radioimmunoassay with Unger antibody
30K (20). For determination of amino acids, plasma proteins were removed by precipitation with sulfosalicylic acid (21). Amino acids were then determined by automated ion exchange chromatography (22) with a Beckman 120C amino acid analyzer (Beckman Instruments, Inc., Spinco Div., Palo Alto, Ca.) modified for single column analysis of basic as well as acidic and neutral amino acids
(23).
For determination of [^T] glucose specific activity, plasma samples were centrifuged immediately and plasma deproteinized using ZnS04 and Ba (0H)2 (24).
The filtrates were analyzed for glucose content by the glucose oxidase method as previously described. Aliquots (0.5 ml) of plasma filtrates were then evaporated to dryness in counting vials in a partial vacuum at 70°C to eliminate metabolic T2O. The dried residues were redissolved in one ml of water, to which 10 ml of aquasol was added for counting (Packard Model 3003 Tri-Carb
Liquid Scintillation Spectrometer, 78% efficiency, with internal quenching).
RESULTS
Hyperglycemic clamp: Prior to NH^Cl the fasting blood glucose concentration averaged 94-3 mg/dl. Durino the period of sustained hyperglycemia the mean glucose concentration of the five subjects was 215-4 ma/dl. Following NH^Cl the fastina blood glucose and steady state hyperglycemic levels averaged 92-1 mq/dl and 218-1 mg/dl respectively. The stability of the blood glucose concentration during the period of hyperglycemia is shown by the coefficient of variation which averaged 3.9-0.61 during the control studies and 3.6-0.7% post NH4CI.
The amount of glucose metabolized (M) during the hyperalvcemic clamp decreased from 9.09 ma/kg body wt./min. to 7.43 mg/Kq body wt./min. followina NH4CI (p<0.10. Table 2). The fasting plasma insulin concentration in the 12 subjects following NH4CI (17-1 yU/ml) was significantly hiqher than during the control study (13 - 1 yU/ml, p 0.02).
Following the creation of a square wave plateau of hyperglycemia, the plasma insulin response was biphasic with an early burst of insulin within the first six minutes followed by a gradually increasing phase of insulin release that lasted until the end of the study. There was no difference in the early insulin response (0-10 min.) between the control and NH4C1 studies (Table 2, Figure 1). However, the late insulin response
(10-120 min.) tended to be greater following the induction of metabolic acidosis and the plasma insulin concentration was statistically significantly higher during the 10-60 minute period. Tissue sensitivity to insulin
(M/I ratio) post NH^Cl decreased in all five subjects by an average of
32-6% (Table II, p<0.02).
The fastina plasma alucaaon concentration in the twelve subjects following NH4CI was significantly higher than during the control study
(110 ± 18 pa/ml versus 95 - 17 pg/ml, p<0.01). Followinq the creation of a steady state plateau of hyperglycemia, plasma olucagon concentration was suppressed similarly in both the pre and post NH4CI studies (Figure 2).
Euglycemic Clamp (Table 3).
The prime-continuous insulin infusion resulted in a steady state plasma insulin level (10-120 minutes) that averaoed 114 - 4 yli/ml during the control study and 110-6 yll/ml following the induction of metabolic acidosis with NH4CI (Fiqure 3). The stability of the plasma insulin concentration is shov/n by the coefficient of variation which averaoed
9-1% durina the control study and 10 - 1% followinq NF^Cl. There was no difference in the metabolic clearance rate of insulin (insulin infusion rate divided by the increase above basal in the 40-120 minute insulin concentration) between the control (415 - 23 ml/min./M2) and acidotic
(412 - 27 ml/min/M^) studies.
The fastina plasma glucose concentrations during the control and
NH4CI studies were 91-2 mg/dl and 88 - 1 mo/dl. During the period of hyperinsulinemia, the plasma alucose concentration was held constant at the basal level with a mean coefficient of variation of 4.7 - 0.4% and 4.2 - 0.3% respectively.
The amount of glucose metabolized following NH4CI decreased from
7.13 - 0.77 to 6.15 - 0.54 mo/kg body wt/min (p=0.07) and the M/I ratio declined from 6.33 - 0.60 to 5.61 - 0.^5 in units of (mg/kq/min per yU/ml)
X 100 (p<0.10).
Followinq the infusion of insulin and olucose, plasma olucaoon
suppressed normally during the control study (p<0.01, figure 4).
Following the induction of metabolic acidosis with NH^Cl, the suppression of glucagon by insulin and glucose was less complete, becoming statistically significantly different at only the 105 and 120 minute values. Plasma amino acid concentrations were measured in subjects M.K., A.P., and M.S.
No difference in fasting levels were observed between the control and
NH4CI studies. Following the creation of hyperinsulinemia, a decrease in the levels of valine, leucine, isoleucine, phenylalanine, threonine, tyrosine, methionine, and serine was observed.
DISCUSSION
Previous studies examining the effect of metabolic acidosis on glucose metabolism have yielded conflicting results. Several reports have suggested that ammonium chloride-induced metabolic acidosis results in an impairment of the intravenous glucose tolerance test and decreased tissue sensitivity to exogenous insulin (3-6). However, several investigators have failed to find a decrease in glucose tolerance (10,15) and the plasma insulin response to glucose following metabolic acidosis has not been reported.
In the present study we employed the glucose clamp technique to examine the relative contributions of impaired beta cell secretion of insulin versus tissue insensitivity to insulin in the genesis of the glucose intolerance following chronic ammonium chloride induced metabolic acidosis.
This technique offers several advantages over the usual techniques employed to assess glucose metabolism:
(1) During the hyperglycemic clamp the glucose stimulus presented to the beta cell is controlled; thus, repeat studies of beta cell sensitivity can be accurately interpreted and compared before and after induction of metabolic acisosis. Furthermore, since the glucose stimulus is presented as a square wave one can examine the early and late phases of insulin secretion independently.
(2) In both the hyperglycemic and euglycemic clamps, the plasma glucose concentration is held constant. Consequently, the amount of glucose infused must equal the amount of glucose metabolized by all the tissues of the body (minus urinary glucose losses) and thus allows quantitation of the glucose metabolized.
(3) The euglycemic clamp offers major advantages over the insulin tolerance test in assessing insulin sensitivity, since the basal glucose concentration is maintained, thereby avoiding the complex neuro-endocrine response to hypoglycemia. The test thus provides a purer estimate of sensitivity to insulin.
(4) Tissue insensitivity to insulin could reside in peripheral tissues (muscle, adipose) or in the liver. By performing the euglycemic clamp in combination with [^T] glucose the contribution of increased hepatic glucose production to the observed insulin resistance can be determined.
(5) The hyperglycemic and euglycemic clamps provide independent tests of the sensitivity of the body to endogenously-released and to exogenously-administered insulin.
The results of the hyperglycemic and euglycemic clamps clearly demonstrate that metabolic acidosis results in the impairment of glucose tolerance and that the effect of acidosis is mediated via decreased sensitivity to insulin. During the hyperglycemic clamp, a decline in glucose metabolism was observed despite a 26% increase in the plasma insulin response. Consequently, the M/I ratio (a measure of tissue sensitivity
to insulin) fell significantly in all five subjects by an average of
32% (p<0.02). The presence of insulin resistance is also suggested
by the elevated fasting insulin levels in the face of normal glucose
concentrations.
Seven subjects also received a euglycemic clamp study to provide an
independent measure of tissue sensitivity to insulin. Tissue sensitivity
to insulin declined in 6 of the 7 by an averaae of 1 2%. When the
results of the euglycemic clamp are combined with those of the
hyperglycemic clamp a hiahly significant decline (p<0.01) in tissue
sensitivity to insulin following metabolic acidosis is observed. These
results indicate that mild metabolic acidosis (mean decline in blood pH and
serum bicarbonate concentration = 0.04 and 4 mE q/L respectively) results
in decreased glucose tolerance which is mediated via tissue insensitivity
to insulin. Beta cell sensitivity to olucose is not affected and insulin
secretion is augmented in an attempt to overcome this insulin resistance.
It is likely that more severe dearees of metabolic acidosis which are maintained for longer periods of time will result in even areater insulin
resistance. Attempts to administer ammonium chloride loads nreater than
0.15 grams/kg body wt/day in human subjects were poorlv tolerated and
the effect of more severe acidosis on olucose metabolism could not be
examined.
The studies with [^T]-qlucose suooest that the insulin resistance
resides in the periphery rather than with the liver. Prior to the
administration of NH^Cl, basal hepatic glucose production averaaed 1.85 mg/kg/min. Following NH^Cl basal glucose production was unchanged.(Table V).
Thus, unlike ranal gluconeoaenesis which is stimulated bv metabolic
acidosis (25), hepatic glucose production appears to be unaffected.
Although these results exclude augmented basal hepatic olucose production as the cause of the observed insulin resistance, it is still possible that incomplete suppression of glycogenolysis and/or gluconeogenesis by insulin is responsible for the decline in glucose tolerance. The answer to this question awaits final completion of the
pT] glucose data. Although basal plasma glucagon levels were mildly elevated following NH4CI, it is unlikely that such a small increase could have any significant effect in augmenting hepatic glucose production on a sustained basis (26). Furthermore, both hyperinsulinemia and hyperglycemia resulted in normal glucagon suppression in the presence of systemic acidosis.
It is well known that insulin lowers the systemic concentration of certain amino acids, most notably valine, leucine, isoleucine, methionine, tyrosine, and phenylalanine (27). This effect of insulin appears to be the result of net inhibition of amino acid output from muscle (28). To examine whether the insulin resistance observed with glucose metabolism also extends to amino acid metabolism, we measured
the fall in circulating amino acids during the euglycemic clamp studies
in three subjects. Following the administration of insulin a prompt decline in plasma valine, leucine, isoleucine, methionine, tyrosine,
phenylalanine, and serine was observed in all subjects both before and after NH4Cl.*Thus, it appears that the insulin resistance observed following the induction of metabolic acidosis is specific for carbohydrate metabolism.
* TABLE IV
SUMMARY:
The effect of metabolic acidosis on glucose metabolism was examined in 12 healthy volunteers employing two types of glucose clamp experiments.
Each subject was studied before and after the ingestion of 0.1 gm of ammonium chloride per kg body wt. per day for three days. For all subjects, the fasting insulin concentration rose significantly without change in the fasting glucose concentration.
Hyperglycemic clamp: The plasma glucose concentration is acutely raised and maintained at 125 mg/dl above the fasting level for two hours by the periodic adjustment of a variable glucose infusion. Since the glucose concentration is held constant, the glucose infusion rate is on index of glucose metabolism (M). Following ammonium chloride M declined from 9.09 to 7.43 mg/kg body wt/min (p=0.10) despite a rise in plasma insulin response. Consequently, the M/I ratio, an index of tissue sensitivity to endogenous insulin, declined in all subjects by 35% (p<0.005).
Euglycemic clamp: The plasma insulin concentration is acutely raised approximately 100 U/ml above basal levels and is maintained by a prime- continuous insulin infusion. The blood glucose concentration is held constant by a variable glucose infusion. M/I is again a measure of time sensitivity to exogenous insulin and fell by 10% (p=0.09). A normal decline in plasma amino acids value, leucine, isoleucine, methionine, tyrosine, phenylalanine, and serine was observed both before and after the induction of metabolic acidosis.
Both the hyperglycemic and euglycemic clamp techniques demonstrate tissue insensitivity to insulin following NH4CI induced metabolic acidosis. The tissue resistance to insulin is specific for glucose metabolism and does not extend to amino acid metabolism.
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Figure 1. The time course of the mean plasma insulin concentration during the hyperglycemic clamp in normal subjects pre ( © ) and post (O ) ammonium chloride. The height of the bars represent the EM.*=P <0.05; **=P <0.02. Figure 2. The time course of the mean (-SEM) plasma glucagon concentration during the hyperglycemic clamp in normal subjects pre and post ammonium chloride. *=P< 0.005; **=P <0.05. Figure 3. The time course of the mean (*SEM) plasma insulin concentration during the euglycemic clamp in normal subjects pre arid post ammonium chloride. *=P< 0.05; **=P <0.02. Figure 4. The time course of the mean (-SEM) plasma glucagon concentration during the euglycemic clamp in normal subjects pre and post ammonium chloride. *=P <0.02; **=P <0,05.
Figure I ro & O) oo o iv) ) UU/ml CONCENTRATION INSULIN PLASMA lOOOOOOOO
TIME (minutes)
140 r- I Figure 2 ro (D cd o ro (pg/ml) CONCENTRATION GLUCAGON PLASMA o o o o o o o -40 -20 0 20 40 60 80 100 120
Figure 3 no ^ o oo o ro (//,U/ml) CONCENTRATION INSULIN PLASMA oooooooo
TIME ( m inutes )
Figure 4 po ^ o oo 4^ o> ro (pg/ml) CONCENTRATION GLUCAGON PLASMA oooooooo -180 -120 -60 0 20 40 60 80 100
OBESITY FBS BLOOD pH SERUM HC03 (mEg/L) SUBJECTS AGE SEX HEIGHT(cm) WEIGHT(kg) INDEX (mg/dl) PRENH4CI POST NH4C1 PRE NH4CL POST NH4CL Q.< Q o iu z:1— >- _1CQ lu s: O' CL. CD CM ODr—CDLf) CM CM O CO O co r-** r*-.r-o O cd 0 CM CD CD COI—CMr— cd toco+1cor^uoco^ra)r^cD+i cm ^co1—GOLoro^rcD'^rcMcD0 LD 00<3-CDCOCM o CM CM cm o CO ■‘d- co co ooc00 O O CD CM CM CM CD CM1—CO O O CO cr> cocd+i DC 21'O Z CL2 CM CM CD O o CO O CM CM CM CM ,_ CM CO CM O O o D- CM CD CO CD CM D- es; LU CD o o z: -h LU OO +1 CM +1 +1 o +1 O O LD o +1 LU O >- Q_ CD UJ o ZD —I CD C CM LD CM r—Or—CTYOCOO^T O O CM CM ld co OOl^'tCMr-r-^CJ) CDOCOCOCDCOr^O')Ln CO CD OYCO D»* OCDCO(T> r^r^.r^r>.r^r^.r^.r^O r^r^r^r^r^r^r^r^o co^-cocorococoooO r^ocricr>r^^-o-)r^^” o Q CM CM CO CM 1— CM «d* *=3*COO O O CM o zc CM CO O LD O CM »xj- CD o CM ,_ CM CO O CM CD O •=£ Cl. CM ,_ O CD O CM CO o CM CM co O 0 DC CM CD O CM O Q. r^. r-.+1 CD CD LDCM cd O'*+1 CO or_ CM CM r- CM LD LU Glucose Metabolism (M), Plasma Insulin Response, and Tissue sensitivityTo Insulin During the Hyperglycemic Clamp Pre and Post NH-C1 •»- ca: sz o * -r- 4-> h-O ro O<*\J ea o .JE c h- OJ —I < r- LU O < o QC o c E s zc < UJ X o < O o ZI o C£ co o rn co o o -f- ^3" cn CO CO o E 03 SUBJECTS M(20-120 min) Plasma Insulin Cone. Change in Insulin Metabolic Clearance Rate (mg/kg/min) (10-120 min) Sensitivity (M/I) (ml/min/M^) (nU/ml) C CD CD CD CD oo lO o *5* O CTi CO + co os O ro + *3" CD CO O r— CO CD CD o CD o r- O o O c_ o O _Q 03 r- E 2: +-> C E rO DURING THE EUGLYCEMIC CLAMP «^C oo 1 ) BASAL GLUCOSE PRODUCTION YALE MEDICAL LIBRARY Manuscript Theses Unpublished theses submitted for the Master’s and Doctor’s degrees and deposited in the Yale Medical Library are to he used only vith due regard to the rights of the authors. Bibliographical references may re noted, but passages must not he copied without permission of the authors, and without proper credit being given in subsequent written or published work. This thesis by has been used by the following persons, whose signatures attest their acceptance of the above restrictions. DATE