Pre- and postganglionic sympathetic nerve activity during induced hypotension with adenosine or sodium nitroprusside in the anesthetized rat.
The aim of this study was to examine the effects of adenosine (AD)-induced hypotension on preganglionic adrenal (aSNA) and postganglionic renal (rSNA) sympathetic nerve activity. rSNA (n = 10) and aSNA (n = 6) were recorded together with mean arterial pressure (MAP) and heart rate (HR) in chloralose-anesthetized, artificially ventilated rats. In each experiment, hypotension was induced by equihypotensive doses of AD (0.03-2.0 mg.kg-1.min-1) and sodium nitroprusside (SNP) (1-10 micrograms.kg-1.min-1). SNP induced a progressive reflex tachycardia and a reflex increase in rSNA to levels 159 +/- 35% above control at a MAP reduction of 55% of the normotensive control value. Equipotent doses of AD induced a decrease in HR and significantly less pronounced reflex increase in rSNA. The maximal increase in rSNA with AD was 55 +/- 19% at a MAP reduction of 30%. At higher infusions rates of AD, rSNA progressively declined toward the normotensive control values. However, AD elicited a progressive increase in preganglionic aSNA that was not significantly different from the increase seen during SNP infusion. It is concluded that AD-induced hypotension is associated with a suppression of postganglionic sympathetic nerve activity caused by an inhibition of ganglionic neurotransmission.
Delle
M
M
Department of Physiology and Anesthesia, Sahlgren's Hospital, University of Göteborg, Sweden.
Ricksten
S E
SE
Delbro
D
D
D000241:Adenosine / Q000494:pharmacology*; D000311:Adrenal Glands / Q000294:innervation; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005292:Ferricyanides / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects; D007023:Hypotension, Controlled; D007668:Kidney / Q000294:innervation; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013564:Sympathetic Nervous System / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects
D005292:Ferricyanides; D009599:Nitroprusside; D000241:Adenosine