title: Effect of sympathectomy on renal and circulatory action of atrial natriuretic peptide.
abstract: Sympathetic nervous system (SNS) involvement in cardiovascular (CV) and renal actions of atrial natriuretic peptide (ANP) was examined in eight chronically instrumented rats. Responses to 90-min atriopeptin II infusion (0.03 then 0.3 micrograms.kg-1.min-1) were compared with those to sodium nitroprusside (NP; 2 + 20 micrograms.kg-1.min-1) before and after sympathectomy (SX) with 6-hydroxydopamine (6-OHDA). The NP-induced drop in blood pressure (BP) was greater after SX (-12 +/- 1% before vs. -24 +/- 2% after SX). In contrast, 6-OHDA altered (blunted) only the bradycardic response to high dose of ANP (-23 +/- 5% before vs. -3 +/- 4% after SX). The decreased BP (-18 +/- 1% before vs. -12 +/- 2% after), depressed cardiac output (CO; -29 +/- 1% before vs. -22 +/- 3% after), and elevated systemic vascular resistance (SVR; 16 +/- 2 vs. 16 +/- 6%) were unchanged (paired t test, P greater than 0.05). The high dose of ANP increased urine flow by 43.2 +/- 7.2 microliters.min-1.100 g body wt-1 and sodium excretion by 1.76 +/- 0.56 mu eq.min-1.100 g body wt-1 but had no effect after SX. These results suggest that while withdrawal of SNS activity contributes to the CO-lowering effect of ANP, it does not mediate its action to elevate SVR. Attenuation of the capacity for reflex sympathoexcitation by SX did not reveal a vasodilator action. The lack of response after SX suggests that ANP's renal excretory actions are mediated in part by withdrawal of SNS activity.
authors: Physiology Program, School of Life and Health Sciences, University of Delaware, Newark 19716.
authors: D E
authors: DE
authors: Allen
mesh_terms: D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D001775:Blood Circulation / Q000187:drug effects*; D002319:Cardiovascular System / Q000187:drug effects; D006400:Hematocrit; D006892:Hydroxydopamines / Q000494:pharmacology; D007668:Kidney / Q000187:drug effects*; D008297:Male; D009498:Neurotoxins / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D016627:Oxidopamine; D010446:Peptide Fragments; D051381:Rats; D011919:Rats, Inbred Strains; D013563:Sympathectomy, Chemical; D013564:Sympathetic Nervous System / Q000502:physiology*
chemical_list: D006892:Hydroxydopamines; D009498:Neurotoxins; D010446:Peptide Fragments; D009599:Nitroprusside; D009320:Atrial Natriuretic Factor; D016627:Oxidopamine; C062524:atrial natriuretic factor prohormone (103-125)