title: Prolonged hyporesponsiveness of airway smooth muscle to histamine following general anesthesia.
abstract: The prolonged effect of barbiturates and inhalation anesthesia on airway response to histamine was studied in five groups of dogs. Group B (n = 10), H24 (n = 5), and H72 (n = 5) were anesthetized with sodium thiamylal (B) or halothane and N2O (H24, H72) for 3 h, during which a dose-response curve to histamine was obtained. The animals were then allowed to recover; 24 h (B and H24) or 72 h later, the animals were killed and an in vitro dose-response curve to histamine was obtained on a tracheal smooth muscle (TSM) specimen. Group C (n = 5), the control group, had no prolonged exposure to anesthesia. The dogs were immediately killed and the in vitro histamine response of the TSM was measured. The results (mean +/- SE) showed that the smooth muscle contractile properties (i.e., the maximum contraction to electrical field stimulation) were comparable in all four groups: 111 +/- 12 g (B); 168 +/- 23 g (H24); 106 +/- 32 g (H72); and 107 +/- 31 g (C). The maximum response (mean +/- SE) to histamine (as % of maximum electrical contraction) was: 15 +/- 6% (B), 30 +/- 9% (H24), 32 +/- 12% (H72), and 50 +/- 8% (C). Statistical analysis of the data showed that the histamine response of Group B and Group H24 was significantly decreased compared to Group C (P less than 0.01 and less than 0.05, respectively); in Group H72 the results were not significantly different from Group C (0.1 greater than P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000768:Anesthesia, General; D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006221:Halothane; D006632:Histamine / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009609:Nitrous Oxide; D013840:Thiamylal
chemical_list: D013840:Thiamylal; D006632:Histamine; D009609:Nitrous Oxide; D006221:Halothane