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The Effects on Renal Resistance to Blood Flow of Renin, Angiotonin, Pitressin and Atropine, Hypertension, and Toxemia of Pregnancy

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The Effects on Renal Resistance to Blood Flow of Renin, Angiotonin, Pitressin and Atropine, Hypertension, and Toxemia of Pregnancy THE EFFECTS ON RENAL RESISTANCE TO BLOOD FLOW OF RENIN, ANGIOTONIN, PITRESSIN AND ATROPINE, HYPERTENSION, AND TOXEMIA OF PREGNANCY Harold Lamport J Clin Invest. 1942;21(6):685-695. https://doi.org/10.1172/JCI101345. Research Article Find the latest version: https://jci.me/101345/pdf THE EFFECTS ON RENAL RESISTANCE TO BLOOD FLOW OF RENIN, ANGIOTONIN, PITRESSIN AND ATROPINE, HYPERTENSION, AND TOXEMIA OF PREGNANCY' By HAROLD LAMPORT' (From the Departmen of Neurology, CoUege of Physicians and Surgeons, Columbia University, and The Neurological Institute, New York City) (Received for publication May 8, 1942) The interpretation of the observations on the Here Pm is the mean of systolic and diastolic blood clearances of inulin and diodrast, as measures of pressure; Po is the osmotic pressure of the systemic blood rate of glomerular filtration and of renal plasma (F = 0), while Po' is the osmotic pressure of the blood after a fraction, F, of the plasma has been filtered off in the flow, has been handicapped by lack of quantita- glomerulus. These pressures are measured in millimeters tive criteria of changes in afferent and efferent of mercury. D is the diodrast clearance or effective renal renal arteriolar resistance. Most of the quali- plasma flow in cc. per minute per individual, or per unit tative criteria suffer because they do not take surface area. No allowance is made for discrepancy be- account of simultaneous changes in blood pres- tween D and effective plasma flow. I is the inulin clear- ance in the same units as D. F = IID. S is the concen- sure, and because they over-simplify by ascribing tration of serum protein in grams per 100 cc. No correc- the effect either to the afferent or the efferent tion for A : G ratios differing from our standard of 2.20 arterioles alone. Where so many factors are has been applied, but means for such adjustment are avail- interrelated, as in the components determining able where the ratios are known (2). H is the reciprocal renal arteriolar resistance, mathematical rela- of 1-hematocrit, expressed as a fraction of 1, and HD is therefore effective renal blood flow. Since Corcoran and tionships are necessary. We have previously Page in their animal experiments found the rate of renal offered formulas for renal arteriolar resistance blood flow in the exteriorized kidney by the Fick principle, (1, 2). They have here been applied to data on analyzing arterial and renal venous blood directly for both renal function in dogs, and also in man, pub- phenol red and inulin, we use the average of their plasma lished by Corcoran and Page et al. (3 to 7), whom flow values derived from these two substances for our D. we wish to thank for their kindness in putting PG, glomerular intra-capillary pressure, is given by the at our approximation, Po' + 20 (1). disposal supplemental and unreported The sum of arteriolar resistance is R = RA + Rs. Being observations.3 We are also grateful to Mr. Julius resistances, each of these symbols is properly expressed in Stein for his painstaking aid in computation. terms of the units of the formulas: millimeters of mercury per cc. individual's own blood per minute per individual, METHOD or per unit surface area. In all cases, except those with The formulas for afferent and efferent renal arteriolar toxemia of pregnancy, the resistance is referred to the resistance are respectively: individual's own blood as standard perfusing medium, so D PM Po' -40 that the resistance values for one individual are not quite - HD comparable with those of another. (1 - 0.47F)(Po' -Po + 10) In many of the experiments reported, there is more than HD one control or experimental period. Strictly speaking, the resistance of the afferent and efferent arterioles for each Pot 2.34S observation should be calculated separately, and averaging 1 - 0.0542S - F of the whole set of final resistances should be done. How- 1 Presented in part at the March, 1942, meeting of the ever, in a trial series, we studied this method as compared American Physiological Society. to averaging the individual quantities from which a single 2Now at the Department of Physiology, Yale Uni- resistance is drawn and found no statistically significant versity School of Medicine, New Haven. difference. Consequently, we have adopted this simpler 'The supplemental data were the hematocrit values method of computation, except in a few instances where which are here supplied in full in the form of 1/(1-hemato- wide variability within the periods to be averaged sug- crit) H. All unreported cases are indicated as such in gested individual calculations. For the sake of complete- the tables, where all the data for calculation are supplied. ness, we restate the results of Corcoran and Page for blood We are assured by the authors that the technique and pressure, renal blood flow, and glomerular filtration rate; conditions of the unreported cases were the same as those the values for glomerular intra-capillary pressure and for already reported, with which they are included. arteriolar resistance and its related quantities are original. 85 686 HAROLD LAMPORT The precision of measurement of renal arteriolar resist- 3. Effect of renin ance is touched on elsewhere (1,2). It is, of course, clear that results drawn from a formula depend on the accuracy Aside from the increase in blood pressure, and of the data applied. The measurements of clearance are fall in renal blood flow (3), renin consistently subject to an error estimated at about 10 per cent. In increased renal arteriolar resistance but, while evaluating results, the quality and mass of the data must the increase was predominantly afferent 6 times, be considered. We shall not report conclusive changes in was in 8 times. There numerical quantities, since here this does not seem war- it mainly efferent origin ranted. However, while it may be incorrect to say, for was a fairly consistent rise in glomerular intra- example, that a 42 per cent increase in a particular quantity capillary pressure, and an inconsistent tendency was noted, it may be statistically legitimate to report in to fall in glomerular filtration rate (Table II). such an instance simply that an increase occurred. 4. Effect of angiotonin in dogs RESULTS We are indebted to Corcoran and Page for 1. Effect of pitressin permitting the use of their published experiments Eight experiments were performed on un- with angiotonin (4), and for supplying data anesthetized dogs after the initial results of supplemental to these published reports. From pitressin had worn off (3). No consistent change them have been selected those cases in which in glomerular intra-capillary pressure occurred, calculation showed the glomerular intracapillary It is nor do changes appear correlated to the degree pressure to be less than blood pressure. our formula for intra- of blood pressure shift, which is mainly that of possible that glomerular capillary pressure, which depends on the Adairs' slight, usually inconsequential, increase. Total and observations on osmotic pressure of renal arteriolar resistance, while it changed con- Greaves' diluted serum (8), is incorrect at high degrees of siderably, was not consistent in direction. There hemoconcentration. There are technical- diffi- is also no consistent change in the ratio of afferent culties, too, in the measurement of renal blood to efferent arteriolar resistance; half of the cases flow and inulin clearance during the rapid fluc- showed an increase and the other half a decrease. tuations produced by angiotonin. For these The suggestion that constriction of the efferent reasons, as well as the possibility that the for- arterioles occurs during periods of reduced renal mulas may not apply at very high degrees of blood flow is not supported by the calculations. vasoconstriction (2), the results for angiotonin No particular anatomical site of action or func- are subject to doubt. Their similarity to those tional effect of pitressin is revealed (Table I). obtained with renin suggests, however, that they are probably not too unreliable for a first esti- 2. Effect of atropine after pitressin mate of the effect on renal resistance of angio- While the addition of intravenous atropine to tonin, particularly in view of the current interest pitressin, as previously reported (3), did not con- in this drug and the, as yet, unsupported opinions sistently affect renal blood flow, blood pressure of its mode of activity. was markedly elevated, and glomerular filtration Renal blood flow fell, blood pressure rose, and rate was increased. Despite the marked blood renal resistance increased markedly during angio- pressure increase, glomerular capillary pressure tonin infusion in the cases selected as noted. rose considerably in only 2 of the 5 cases, out The increased resistance cannot here be ascribed of a total of 7, in which an increase was recorded, primarily to afferent or efferent arteriolar con- and in these 2 cases the blood pressure shift was striction. On the whole, glomerular intra-cap- minor. Statistical analysis reveals that the in- illary pressure rose. Changes in glomerular crease is not significant (23 per cent likelihood filtration rate were not consistent (Table III). of chance alone being responsible). In all cases, total arteriolar resistance rose, with afferent 5. Effect of angiotonin in man arteriolar constriction predominating in all but Figure 1 shows the previously reported results 1 case. In fact, the efferent arterioles dilated of angiotonin infusion in a single human subject in 4 of the 7 cases (Table I). (5). The calculations of total arteriolar resist- EFFECTS ON RENAL RESISTANCE TO BLOOD FLOW 687 8 0 c c a a! .!2 -'4 COt-.I4 -000 0on i41% " -- .bqw 4 s I m C4 O in0%*(Q4ciCDUl) No. 000i 40 ' (It W4 6 C-4 W4 1; '.4'.4'.
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