PRESSURE-INDUCED CONTRACTION OF THE JUXTAMEDULLARY AFFERENT ARTERIOLES IN SPONTANEOUSLY HYPERTENSIVE RATS

1. In the SHR juxtamedullary nephron preparation, the increase of the perfusion pressure from 80 to 160 mmHg increased the diameters of arcu ate arteries but produced a pressure-dependent contraction of the affe rent arterioles, a response that can account for renal autoregulation. 2. The pressure-induced contractions of the afferent arterioles were abolished by 1 mu M nifedipine and by 10 mu M furosemide, suggesting t hat the autoregulatory responses are mainly mediated by tubuloglomerul ar mechanisms and can be abolished by calcium antagonists.