Hill B J, Katwa L C, Wamhoff B R, Sturek M
Vascular Biology Laboratory, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA.
J Pharmacol Exp Ther. 2000 Nov;295(2):484-91.
Arterial injury models for coronary artery disease have demonstrated an enhanced expression and function of either the endothelin(A) or endothelin(B) (ET(A) or ET(B)) receptor subtype. We hypothesized that organ culture would enhance the physiological function of ET receptors in the porcine right coronary artery. Arteries were either cold stored (4 degrees C) or organ cultured (37 degrees C) for 4 days. After 4 days, the artery was either 1) sectioned into rings to measure the ET-1-induced isometric tension response (3 x 10(-10)-3 x 10(-7) M), or 2) enzymatically dispersed and the isolated smooth muscle cells imaged using fura-2 to measure the myoplasmic calcium (Ca(m)) response to 3 x 10(-8) M ET-1 ( approximately EC(50)). Isometric tension and Ca(m) to ET-1 were measured in the absence and presence of bosentan (nonselective ET(A) or ET(B) receptor antagonist), BQ788 (ET(B)-selective antagonist), and BQ123 (ET(A)-selective antagonist). Compared with cold storage, organ culture induced a 2-fold increase in tension development (3 x 10(-7) M ET-1) and Ca(m) (3 x 10(-8) M ET-1), which was inhibited with bosentan, thus confirming the enhanced responses to ET-1 were due to ET receptor activation. BQ123 also inhibited the enhanced contraction and Ca(m) responses to ET-1. In contrast, BQ788 failed to inhibit tension development and Ca(m) responses to ET-1 in organ culture and cold storage. Sarafotoxin 6C (ET(B) agonist) failed to elicit an increased Ca(m) response in organ culture compared with cold storage. Our results indicate the increased tension development and Ca(m) responses to ET-1 in organ culture are attributable to ET(A) receptors, and not ET(B) receptors.
冠状动脉疾病的动脉损伤模型已证明内皮素（A）或内皮素（B）（ET（A）或ET（B））受体亚型的表达和功能增强。我们假设器官培养会增强猪右冠状动脉中ET受体的生理功能。将动脉在4℃下冷藏或在37℃下进行器官培养4天。4天后，将动脉：1）切成环以测量ET-1诱导的等长张力反应（3×10⁻¹⁰ - 3×10⁻⁷M），或2）酶解分散，并用fura-2对分离的平滑肌细胞成像以测量对3×10⁻⁸M ET-1（约EC₅₀）的肌浆钙（Ca（m））反应。在不存在和存在波生坦（非选择性ET（A）或ET（B）受体拮抗剂）、BQ788（ET（B）选择性拮抗剂）和BQ123（ET（A）选择性拮抗剂）的情况下测量对ET-1的等长张力和Ca（m）。与冷藏相比，器官培养使张力发展（3×10⁻⁷M ET-1）和Ca（m）（3×10⁻⁸M ET-1）增加了2倍，波生坦可抑制这种增加，从而证实对ET-1的反应增强是由于ET受体激活。BQ123也抑制了对ET-1的收缩增强和Ca（m）反应。相比之下，BQ788未能抑制器官培养和冷藏中对ET-1的张力发展和Ca（m）反应。与冷藏相比，沙拉毒素6C（ET（B）激动剂）在器官培养中未能引起Ca（m）反应增加。我们的结果表明，器官培养中对ET-1的张力发展和Ca（m）反应增加归因于ET（A）受体，而非ET（B）受体。
