Sympathetic modulation of the pressure-dependent renin release in conscious dogs.
The relationship between mean renal artery pressure and renal venous-arterial plasma renin activity-difference (renin stimulus-response curve; RSRC) was studied in 15 conscious dogs by a stepwise reduction of renal artery pressure down to the lower limit of renal blood flow (RBF)-autoregulation. The RSRC has a flat section above threshold and a steep slope - indicating a 100% increase of renin release per 2.5 mmHg - below a well defined threshold pressure (Pth). Pth may remain unchanged for 4 weeks. A reflex activation of the renal sympathetic nerves by common carotid occlusion increased Pth by 16.5 +/- 3.2 mmHg (P less than 0.01); this effect was abolished by intrarenal alpha-blockade (prazosin). A low dose intrarenal infusion of methoxamine, which did not change RBF, increased Pth by 8.5 +/- 0.7 mmHg (P less than 0.001). We conclude that in the resting conscious dog renal perfusion pressure is a powerful factor in the control of renin release. The renal sympathetic nerves modulate the pressure-dependent mechanism within the autoregulatory range of renal blood flow by an alpha-adrenergic adjustment of threshold pressure.
Kirchheim
H
H
I. Physiologisches Institut der Universität Heidelberg, Federal Republic of Germany.
Ehmke
H
H
Fischer
S
S
Löwe
W
W
Persson
P
P
D000818:Animals; D001794:Blood Pressure; D002339:Carotid Arteries / Q000502:physiology; D003243:Consciousness; D004056:Differential Threshold; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D008729:Methoxamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology; D012018:Reflex / Q000187:drug effects / Q000502:physiology; D012083:Renin / Q000378:metabolism*; D012146:Rest; D013564:Sympathetic Nervous System / Q000502:physiology*
D012083:Renin; D008729:Methoxamine; D011224:Prazosin