Hemodynamic failure induced by narcotic and toxic doses of 12 CNS depressants in intact and pithed rats.
Heart rate (HR), cardiac output (CO), stroke volume (SV), arterial blood pressure (BP), and peripheral resistance (PR) were assessed in awake rats and in rats anesthetized with hexobarbital, pentobarbital, secobarbital, secbutabarbital, methaqualone, chloral hydrate, urethane, ethanol, guaiphenesine, meprobamate, diazepam and chlorpromazine (respired artificially). Anesthesia mostly was accompanied by an increase of HR and PR and a decrease of CO and SV, whereas BP remained unchanged or somewhat declined. Infusion of further amounts of the CNS depressants caused a dose-dependent decrease of HR, CO and BP but did not influence SV whereas PR declined but did not fall considerably beyond the values in awake rats. A strong decline of CO, SV and BP but no change of HR and PR occurred after pithing in rats. Anesthetic doses of hexobarbital, pentobarbital, secobarbital, secbutabarbital, methaqualone, and guaiphenesine produced no hemodynamic effects in pithed rats. Chloral hydrate, urethane, ethanol, meprobamate, diazepam, and chlorpromazine, on the other hand, in anesthetic doses depressed the CO and BP of pithed rats without influencing PR. In toxic doses, the CNS depressants caused comparable hemodynamic changes in pithed as in anesthetized rats.


CONCLUSIONS
Hemodynamic failure induced by narcotic doses of CNS depressants is mainly due to a depression of the vasomotor center(s) and an impairment of cardiovascular reflex control, that after toxic doses is mainly caused by the direct cardiovascular-depressive actions of these drugs.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D006993:Hypnotics and Sedatives / Q000494:pharmacology* / Q000506:poisoning; D008297:Male; D051381:Rats; D013116:Spinal Cord / Q000502:physiology; D013318:Stroke Volume / Q000187:drug effects; D014149:Tranquilizing Agents / Q000494:pharmacology* / Q000506:poisoning; D014655:Vascular Resistance / Q000187:drug effects
D006993:Hypnotics and Sedatives; D014149:Tranquilizing Agents