Effects of oxygen tension on vascular and other smooth muscle.

1. The resting tension of various isolated intestinal and vascular smooth muscle preparations varied directly with the P(O) (2) of the stream of blood used to bathe them.2. This effect was also obtained when artificial salt solution was used and was therefore not due to circulating hormones.3. The effect could not be antagonized by specific pharmacological antagonists such as hyoscine, phenoxybenzamine, hexamethonium, bromolysergic acid, diethylamide or mepyramine.4. The reactions of the isolated organs to catecholamines and 5-hydroxytryptamine (5-HT) were increased by the higher P(O) (2).5. These results support the view that oxygen tension may play a major role in autoregulation of blood flow.