AJP - Regulatory, Integrative and Comparative Physiology, Vol 242, Issue 5 552-R562, Copyright © 1982 by American Physiological Society
Neural and vascular interaction in renin response to graded renal nerve stimulation
W. S. Ammons, S. Koyama and J. W. Manning
The effect of a 1-min period of renal nerve stimulation was studied in
alpha-chloralose-anesthetized cats, whose left kidneys were pump perfused.
Renal hemodynamics and filtration parameters were unaltered at stimulation
frequencies of 2.0 Hz or less; however, renin secretion rates (RSR)
increased with frequency reaching 3 times the control level. At higher
frequencies renal vasoconstriction occurred and glomerular filtration rate
(GFR) fell. RSR was increased but little more than at 2.0 Hz. The RSR
response plots were similar to constant-flow and constant-pressure perfused
preparations. beta-Adrenergic blockade with propranolol abolished
low-frequency responses and resulted in progressive decreases in RSR at
higher frequencies. alpha-Adrenergic blockade with phentolamine prevented
renal vascular and GFR changes, whereas RSR continually increased up to
12.0 Hz (13.5 times control). Papaverine treatment, to prevent vascular-GFR
changes without blocking alpha-receptors, resulted in similar renin
responses. The results indicate that the beta-adrenergic receptor mediates
increases in RSR in proportion to frequency when vascular-GFR factors are
constant. When renal vasoconstriction occurs at high frequencies the
beta-receptor mechanism interacts with an inhibiting mechanism indirectly
mediated by alpha-adrenergic receptors.
