Collagenase eliminates the electrical responses of smooth muscle to catecholamines

The effects of collagenase on the membrane response to catecholamines were studied with intracellular microelectrodes in the guinea-pig taenia caeci and main pulmonary artery. In the taenia, the inhibitory actions of adrenaline mediated through alpha- and beta-adrenoceptors were both nearly abolished by two 5-min treatments with 0.005% collagenase. In the pulmonary artery, the depolarizing action of noradrenaline mediated through beta-adrenoceptors was markedly reduced by three 5-min treatments with 0.01% collagenase.