Influence of body temperature on histamine-induced bronchoconstriction in guinea pigs

Abstract

The effects of body temperature on histamine-induced bronchoconstriction were investigated in anesthetized, paralyzed, and mechanically ventilated guinea pigs. Four groups of guinea pigs were studied with constant body temperatures of 40, 38, 35, and 32 degrees C, respectively. Histamine was infused for 5 min at a rate of 50 ng.kg-1.s-1. Body cooling from 40 to 32 degrees C augmented the bronchomotor responses to histamine, which eventually rose almost fourfold. The enhancement of histamine-induced bronchoconstriction induced by body cooling was not suppressed by pretreating guinea pigs with 5 mg/kg hexamethonium or 5 mg/kg hexamethonium plus 3 mg/kg atropine; neither was the enhancement of histamine-induced bronchoconstriction suppressed in pithed guinea pigs, demonstrating that the autonomic nervous system is not involved in potentiating bronchoconstriction at low body temperatures. These results suggest that, at low body temperatures, increased airway responsiveness to histamine may be because of some direct effect of temperature on bronchial airway smooth muscle.

Contractile activity of three endothelins (ET‐1, ET‐2 and ET‐3) on the human isolated bronchus

“…The cyclo-oxygenase inhibitor indomethacin (3 x 106 M) does not significantly modify the response to ET-1 on the isolated human bronchus. This is not concordant with the data obtained in vivo in the guinea-pig, where indomethacin (10mgkg-1) or meclofenamate (0.5 to 2mgkg-1) suppressed the bronchoconstriction induced by intravenous or inhaled ET-1 (Payne & Whittle, 1988;Lagente et al, 1989;Macquin-Mavier et al, 1989). The discrepancy may be explained by recent reports showing that the human bronchial smooth muscle may generate important quantities of prostanoids which do not modulate the contractile responses in vitro (Douglas & Brink, 1987;De Jongste et al, 1987;Naline et al, 1989).…”

“…ET-1 administered in vivo either intravenously or by inhalation induces in the guinea-pig a marked and sustained bronchoconstriction which is suppressed by pretreatment with the cyclo-oxygenase inhibitors indomethacin or meclofenamate (Payne & Whittle, 1988;Braquet et al, 1989;Lagente et al, 1989;Macquin-Mavier et al, 1989).…”