[Mechanisms underlying depressor and bradycardia effects of A1-excitation in rats].
In chloral hydrate-anesthetized, tubocurarine-immobilized and artificially ventilated rats, the following results were observed: (1) Microinjection of sodium L-glutamate (Glu) into A1 area induced a significant fall in blood pressure and heart rate. (2) Bilateral vagotomy markedly reduced the magnitude of the depressor and bradycardia effects of Glu-injection into A1. (3) Injection of phentolamine or propranolol into bilateral RVL reduced the depressor effect of Glu-injection into A1. Naloxone-injection into RVL had no significant influence on cardiovascular effects of A1-excitation, but injecting bicuculline into RVL could reverse both depressor and bradycardia effects of A1 area. The results suggest that A1 exerts its cardiovascular effects mainly via RVL, and the alpha-, beta- and GABA-receptors within RVL (but not opiate receptors) mediate the hypotension effect of A1 area, while GABA-receptors play an important role in mediating the bradycardia effect of the A1 area.
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D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D008845:Microinjections; D009270:Naloxone / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
D009270:Naloxone; D011433:Propranolol; D001640:Bicuculline; D010646:Phentolamine