Palmer L S, Valcic M, Melman A, Giraldi A, Wagner G, Christ G J
Department of Urology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, New York 10461.
J Urol. 1994 Oct;152(4):1308-14. doi: 10.1016/s0022-5347(17)32573-9.
Intracavernous pharmacotherapy relies heavily on the use of vasoactive agents which act by increasing intracellular cAMP levels in human corpus cavernosum smooth muscle. Yet little is known about the cAMP generating system in this tissue, and how it may affect observed patient variability. Thus, the goal of these studies was to better characterize the biochemistry of cAMP formation in human corpus cavernosum smooth muscle, and thus provide more insight into the mechanisms of corporal smooth muscle relaxation in vivo. We studied both receptor and nonreceptor mediated increases in cAMP formation in short-term cultures of human corpus cavernosum smooth muscle cells. Both isoproterenol (ISO) and prostaglandin E1 (PGE1) produced concentration-dependent increases in cAMP, but histamine, serotonin and vasoactive intestinal polypeptide did not. Forskolin, a relatively specific activator of adenylate cyclase, was also a potent stimulant of cAMP formation in these cells. Moreover, there was a direct correlation between the degree of forskolin-induced cAMP accumulation in cultured corporal smooth muscle cells and the magnitude of the forskolin-induced relaxation response of precontracted isolated corporal smooth muscle strips. Prostaglandin E1 and ISO concentration response curves (CRCs) were then assayed in the absence and presence of subthreshold forskolin (0.1 microM.). In the presence of forskolin, the calculated maximal PGE1-induced cAMP accumulation (Emax) was significantly greater than that elicited by PGE1 alone, ISO alone, or ISO + forskolin (p < or = 0.02). In addition, a fixed molar ratio (FMR) (PGE1:ISO) protocol was used to demonstrate that both 80:20 and 70:30 FMRs (but not 95:5 or 90:10), were associated with significantly greater cAMP Emax values than that observed for PGE1 alone (p < or = 0.01). These data provide direct evidence that the degree of cAMP formation in cultured corporal smooth muscle cells is strongly correlated with the magnitude of relaxation of isolated corporal smooth muscle strips. In addition, since simultaneous activation of distinct components of the cAMP generating system produces significant increases in maximal intracellular cAMP accumulation, this suggests that such drug combinations may also augment corporal smooth muscle relaxation in vitro and in vivo.
海绵体内药物治疗在很大程度上依赖于血管活性药物的使用，这些药物通过增加人海绵体平滑肌细胞内的环磷酸腺苷（cAMP）水平来发挥作用。然而，对于该组织中的cAMP生成系统以及它如何影响患者的个体差异，我们知之甚少。因此，这些研究的目的是更好地描述人海绵体平滑肌中cAMP形成的生物化学过程，从而更深入地了解体内海绵体平滑肌舒张的机制。我们在人海绵体平滑肌细胞的短期培养物中研究了受体介导和非受体介导的cAMP形成增加。异丙肾上腺素（ISO）和前列腺素E1（PGE1）均能使cAMP产生浓度依赖性增加，但组胺、血清素和血管活性肠肽则不能。福斯高林是腺苷酸环化酶的相对特异性激活剂，也是这些细胞中cAMP形成的有效刺激剂。此外，在培养的海绵体平滑肌细胞中，福斯高林诱导的cAMP积累程度与福斯高林诱导的预收缩离体海绵体平滑肌条舒张反应的幅度之间存在直接相关性。然后在存在和不存在阈下福斯高林（0.1微摩尔）的情况下测定前列腺素E1和ISO的浓度反应曲线（CRCs）。在存在福斯高林的情况下，计算得出的最大PGE1诱导的cAMP积累（Emax）显著大于单独使用PGE1、单独使用ISO或ISO + 福斯高林所引起的cAMP积累（p≤0.02）。此外，采用固定摩尔比（FMR）（PGE1:ISO）方案来证明，80:20和70:30的FMR（但不是95:5或90:10）与单独使用PGE1时观察到的相比，cAMP Emax值显著更高（p≤0.01）。这些数据提供了直接证据，表明培养的海绵体平滑肌细胞中cAMP的形成程度与离体海绵体平滑肌条的舒张幅度密切相关。此外，由于同时激活cAMP生成系统的不同组分可使最大细胞内cAMP积累显著增加，这表明这种药物组合在体外和体内也可能增强海绵体平滑肌的舒张。
