CULTURED ENDOTHELIAL-CELLS FROM DISTINCT VASCULAR AREAS SHOW DIFFERENTIAL RESPONSES TO AGONISTS

We compared the ability of cultured endothelial cells isolated from ra bbit aorta, vena cava, ventricular chamber, and pulmonary microvascula ture to produce relaxing factor(s) in response to acetylcholine (ACh) and bradykinin (BK). Endothelium-denuded rabbit aortic rings were prec ontracted with 1 mu M phenylephrine and superfused at 2 mL/min with Kr ebs-Henseleit bicarbonate buffer. Rings were exposed to 3-mL bolus con trol challenges of 1 mu M ACh or 1 mu M BK. Boluses of ACh or BK were added to dishes of cultured endothelial cells that had been incubated for 45 min in media either with or without 10 mu M N-G-nitro-L-arginin e (NNLA). The resulting solution was applied over the rings within 8 s . Only left ventricular endothelial cells stimulated with ACh and BK, and pulmonary microvascular endothelial cells stimulated with BK produ ced products that relaxed rings by approximately 6 +/- 2%. Incubation with NNLA attenuated these relaxations. Our findings indicate there ar e differences in the abilities of endothelial cells of different anato mical origins to release nitric oxide derived relaxing factors in resp onse to ACh and BK.