DL-PROPRANOLOL AUGMENTS PRODUCTION OF NO-CENTER-DOT INDUCED BY CYTOKINES IN CULTURED AORTIC SMOOTH-MUSCLE OF THE RAT

The effect of DL-propranolol on the production of nitric oxide (NO.) b y cultured arterial smooth muscle cells from normotensive (WKY) and sp ontaneously hypertensive rats (SHR) was studied before and after stimu lation by lipopolysaccharide or interleukin-1 beta. The influence of L -arginine and N-G-nitro-L-arginine on these events was also studied. L ipopolysaccharide-stimulated SHR-derived smooth muscle cells produced less NO. than WKY cells. However the amounts produced in response to i nterleukin-1 beta were similar for the two cell types. DL-propranolol increased the NO. production in both types of cells exposed to lipopol ysaccharide, but had no significant effect on this parameter in WKY-de rived cells exposed to interleukin-1 beta. Inclusion of L-arginine dur ing incubations with propranolol had no effect on levels of NO. produc ed by either cell type exposed to lipopolysaccharide. The basal produc tion NO. was enhanced in smooth muscle cells from both normotensive an d hypertensive rats when the cells were treated with L-arginine after exposure to interleukin-1 beta. L-Arginine increased the response to D L-propranolol only in the WKY cells. NO. production was depressed by i nclusion of N-G-nitro-L-arginine during incubations in both cell types regardless of the treatment regime used to induce NO. synthase activi ty. The results suggest that DL-propranolol may induce the production of NO. by cultured smooth muscle cells exposed to cytokines.