Diazepam facilitates reflex bradycardia in conscious rats.
The effects of diazepam on cardiovascular function were assessed in conscious rats. Intravenous administration of diazepam (1-30 mg kg-1) produced a dose-dependent decrease in both the mean arterial pressure and the heart rate. Also, reflex bradycardia was produced in rats by intravenous infusion of adrenaline (1.25-2.5 micrograms kg-1). Intravenous pretreatment of the rats with diazepam, although causing no change in the adrenaline-induced pressor effect, did enhance the adrenaline-induced reflex bradycardia. However, the diazepam enhancement of adrenaline-induced reflex bradycardia was antagonized by pretreatment of rats with an intravenous dose of picrotoxin (an agent blocks chloride channels by binding to sites associated with the benzodiazepine-GABA-chloride channel macromolecular complex). The data indicate that diazepam acts through the benzodiazepine-GABA-chloride channel macromolecular complex within the central nervous system to facilitate reflex bradycardia mediated through baroreceptor reflexes in response to an acute increase in arterial pressure.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D003975:Diazepam / Q000494:pharmacology*; D004837:Epinephrine / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects*; D007275:Injections, Intravenous; D008297:Male; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D003975:Diazepam; D004837:Epinephrine; D010852:Picrotoxin