Secretory Functions of Smooth Muscle: Cytokines and Growth Factors

Inhibition of vascular smooth muscle contraction by acute exposure to IL-1β depends in part on nitric oxide synthase activity. Rat aorta strips denuded of endothelium were kept 6 hr in short term organ culture and either left untreated (solid line) or exposed to 20 ng/ml IL-1β (dashed line). Panel A shows IL-1β –inhibited phenylephrine-induced contraction. Panel B shows that when the experiment was repeated in the presence of 100 μ M N -monomethyl-l -arginine (LNMMA) to inhibit nitric oxide synthase, the inhibitory effect of IL-1β was markedly reduced. [Results are summarized from Takizawa et al. (35).]