[Effects of cimetidine on plasma concentration of catecholamine and baroreflex control of heart rate in anesthetized humans].
To clarify the mechanism of cardiovascular depression by cimetidine, we studied the effects of intravenous cimetidine on the plasma catecholamine concentration and baroreflex control of heart rate in man before and during enflurane-nitrous oxide anesthesia. Baroreflex control of heart rate was assessed by raising the arterial pressure by phenylephrine. Before anesthesia, 200 mg cimetidine decreased plasma epinephrine concentration (E) from 135 +/- 48 (s.e.) pg.ml-1 at baseline to 91 +/- 35 pg.ml-1 5 min after administration, but there were no significant changes in the norepinephrine concentration (NE), slope of pressor response, systolic blood pressure (SBP) or heart rate (HR). In anesthetized patients, baseline values of E, NE and slope were all significantly decreased as compared to those without anesthesia. However, cimetidine administered during anesthesia decreased both SBP and HR, by 19 +/- 5 mmHg and 9 +/- 6 beats.min-1, respectively, without further decrease of plasma catecholamine or slope by cimetidine than those at baseline. We conclude that inhibition by cimetidine of cardiovascular system during anesthesia is not due to further depression of baroreflex or plasma catecholamine concentration.
Kuramoto
T
T
Ueda
T
T
Hatano
M
M
D000769:Anesthesia, Inhalation; D002927:Cimetidine / Q000494:pharmacology*; D004737:Enflurane; D004837:Epinephrine / Q000097:blood*; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D009609:Nitrous Oxide; D009638:Norepinephrine / Q000097:blood*; D011311:Pressoreceptors / Q000187:drug effects* / Q000502:physiology; D012018:Reflex / Q000187:drug effects* / Q000502:physiology
D002927:Cimetidine; D004737:Enflurane; D009609:Nitrous Oxide; D009638:Norepinephrine; D004837:Epinephrine