title: Effects of halothane on the cyclic 3',5'-adenosine monophosphate enzyme system in human platelets.
abstract: A study of the effects of halothane on the cyclic 3',5'-adenosine monophosphate (cAMP) system in human platelets was undertaken since cAMP has been implicated in the regulation of the process of platelet aggregation and this anesthetic has been reported to decrease platelet aggregation and, in other tissues, to increase adenylate cyclase activity. When exposed to halothane 0.5 to 10 vol%, adenylate cyclase activity was increased in the platelet preparation in a dose-dependent manner, reaching a maximum at 5 vol% (93% increase above basal activity). Platelet aggregation was also inhibited by halothane in a dose-dependent manner, with a maximum effect at about 5 vol% halothane (a decrease of 70%). Kinetic analysis of platelet cAMP-phosphodiesterase suggested two forms of activity, neither of which was altered by halothone. The results that the impairment of platelet aggregation observed with halothane may be brought about by the halothane-induced activation of platelet adenylate cyclase, which may result in a higher cAMP level, inhibiting platelet aggregation.
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000032:analysis*; D000262:Adenylyl Cyclases / Q000097:blood*; D000328:Adult; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D006221:Halothane / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D010727:Phosphoric Diester Hydrolases / Q000097:blood*; D010974:Platelet Aggregation / Q000187:drug effects
chemical_list: D010727:Phosphoric Diester Hydrolases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases; D006221:Halothane