Effect of halothane on contractile function and reactivity of myocardium

Abstract

The influence of halothane on isolated guinea-pig atria beating spontaneously at 29° and on the electrically driven isolated papillary muscle of cat right ventricle at 37°C was studied. In each preparation halothane produced a decrease of the active tension and did not significantly change the spontaneous beating rate of the guinea-pig atria. Halothane significantly reduced the absolute active tension of papillary muscle during the staircase phenomenon and during postextrasytolic potentiation. However, since the basic tension decreased during halothane, the percentage increase during staircase phenomenon and postextrasystolic potentiation, was unchanged in comparison with the control period on the same muscles. Compared with the control period, halothane significantly increased the percentage increase of tension developed either during high voltage stimulation (releasing catecholamines from adrenergic nerve endings) or while adding tyramine or norepinephrine to the isolated papillary m