AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 6 1003-R1008, Copyright © 1984 by American Physiological Society
Activation of afferent renal nerves by intrarenal bradykinin in conscious rats
J. F. Smits and M. J. Brody
Bradykinin was infused intravenously and into the right renal artery of
conscious rats that were chronically instrumented with catheters and
miniaturized pulsed-Doppler flow probes. The effects on regional
hemodynamics were compared with those in animals in which the infused
kidney was denervated as well as in animals anesthetized with pentobarbital
sodium. In intact rats bradykinin (1 microgram/min) caused an immediate
increase in mean arterial blood pressure (MAP, 27 +/- 4 mmHg), heart rate
(HR, 67 +/- 11 beats/min), mesenteric resistance (MR, 32 +/- 10%), and both
right (RRR, 42 +/- 14%) and left renal resistance (LRR 21 +/- 8%). These
effects were significantly different from those during intravenous infusion
of the same dose of bradykinin (MAP, 6 +/- 3 mmHg; HR, 31 +/- 7 beats/min;
MR, -21 +/- 5%; RRR, 8 +/- 4%; LRR, 6 +/- 3%). Pentobarbital greatly
attenuated the responses to intrarenal bradykinin. In conscious animals
denervation of the infused kidney completely abolished the cardiovascular
effects of intrarenal bradykinin. In a separate group of animals,
chlorisondamine (7.5 mg/kg iv) completely blocked the increases in MAP and
HR during intrarenal bradykinin (1 microgram/min). It is concluded that
selective renal administration of bradykinin alters afferent renal nerve
activity and that this results in hemodynamic changes consistent with
efferent sympathetic activation.
