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HANDBOOK OF PHYSIOLOGY 



CIRCULATION II 



table 9. Effect of Apresoline on Renal Hemodynamu s 



in Normal and Nephritic Humans 



GFR RPF RBF FF P A RVR 



A oi mat 



[After Etteldorf et al. (86).] 



table 10. Effects of Serotonin on Renal Hemodynamu * 

 in the Unanesthetized Dog 



[After Spinazzola & Sherrod (294).] 



sure changed from 137 to 1 16 mm Hg, C PAH increased 

 from 343 to 429 ml per min. The dosage was com- 

 parable to die above series. Interestingly, the vaso- 

 constrictive effect of exercise (in patients with mitral 

 stenosis) is counteracted by Apresoline (337). 



Serotonin (5-hydroxytryptamine), an extremely 

 interesting compound produces hyperemia in the 

 kidney (64, 294) and has a striking antidiuretic 

 activity. Spinazzola & Sherrod (294) have studied 

 the effects of graded increase in dosage in unanesthe- 

 tized dogs (table 10). Blood pressure showed no 

 significant changes. Although decrease in GFR con- 

 tributes to the antidiuresis, some other mechanism 

 may be involved (stage 2). Emanuel et al. (83), on 

 the contrary, find that direct infusion into the renal 

 artery in dosage of 10 /zg to 100 ng per min increased 

 vascular resistance. 



Miscellaneous. Histamine has an unpredictable 

 action on renal blood flow (287). The best work ap- 

 pears to be that of Blackmore et al. (22) who adminis- 

 tered 2.5 /zg per kg per min for 2 hours to dogs. 

 Glomerular filtration rate was constant during the 

 infusion, even though blood pressure fell slowly 

 (never below 75 mm Hg). Control RBF was 360.5 

 ml per min (sd, 21.5); after 1 hour, 466.5 (±37.3); 

 2 hours, 487.8; (±39.2); recovery, 434. 1 (±34.2). 

 Bradykinin increases direct blood flow in the dog 

 kidney (g), in the face of decreases in systemic blood 

 pressure. 



Morphine sulfate (30 mg kg) results in significant 

 reductions in C PAH in dogs, while C ln stays constant. 

 Blood pressure declines slightly but active vasocon- 

 striction is indicated (7). 



Xanthine derivatives. In man, theophylline (ami- 

 nophylline) and caffeine increase filtration rate. 

 After a brief and variable increase in C D , this suffers 

 a sustained decrease (287). The initial rise is associ- 

 ated with an increase in cardiac output. Parephvllin 

 (diethylaminoethyltheophylline) has no effect on GFR 

 and RBF in dogs. In man, an initial decrease in 

 GFR and C PAH was noted (187), then a slight in- 

 crease in 20 to 40 min. Filtration fraction showed no 

 change, and blood pressure changes were not signifi- 

 cant. In patients in heart failure, GFR and C PAH 

 paradoxically decreased. 



ANESTHETIC AGENTS AND RENAL BLOOD FLOW. Several 



reviews on the subject (242, 275, 287) have pointed out 

 that all general anesthetic agents significantly dimin- 

 ish renal plasma flow, glomerular filtration rate, and 

 water and electrolyte excretion if there is sufficient 

 depth of anesthesia. During light anesthesia, blood 

 flow through the skin and muscles of the extremities 

 may be increased (242) with vasoconstriction in the 

 splanchnic area, which may include the kidney, so 

 that a redistribution of blood occurs. During pro- 

 longed or deep anesthesia, flow through skin and 

 muscles, as well as in the splanchnic bed, decreases. 



The effects of anesthetic agents are complex, for 

 other factors are introduced which modify the kidney 

 function beyond the direct action of the anesthetic 

 agent itself. Possible changes in systemic arterial and 

 venous pressure would modify renal blood flow. The 

 sympathetic system is stimulated to produce en- 

 hanced neurogenic effects. Catecholamine output goes 

 up in turn causing further vasoconstriction. In deep 

 narcosis, effects of hypoxia and hypercapnia enter 

 the picture because of respiratory depression or airway 

 obstruction. In terms of the water and electrolyte 

 picture, changes occur in endocrine output (e.g., en- 

 hanced activity of the pituitary-adrenal axis, and in- 

 creased ADH output from the neurohypophysis). 

 Finally the kidney's ability to correct acid-base dis- 

 turbances may be impaired. 



Pentobarbital anesthesia. During relatively short 

 periods of action, no consistent change in inulin and 

 Diodrast clearances or Tm D were noted with dosage 

 of 30 mg per kg (61). When the duration of action of 

 pentobarbital sodium and sodium barbital was in- 

 creased to 5 hours by Glauser & Selkurt (103), there 

 was 18 per cent decrease in C PA h, with no change in 



