Giraldi A, Serels S, Autieri M, Melman A, Christ G J
Department of Urology, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
J Urol. 1998 Nov;160(5):1856-62.
Increases in cytosolic calcium levels trigger smooth muscle contraction while nuclear calcium increases are thought to regulate gene expression. Endothelin-1 (ET-1) affects both. The goal of these studies was to further investigate the importance of ET-1 to corporal physiology by examining its actions on proliferation and immediate early gene (IEG) expression in cultured human corporal smooth muscle cells.
MATERIALS & METHODS: Early passage (1-3) smooth muscle cells were grown in culture and exposed to either phenylephrine (PE) or ET-1 in the absence and presence of serum, the ET(A) or ET(B) selective antagonist BQ123 or IRL1038, or the L-type Ca2+ channel blocker, verapamil. Cell proliferation was assessed with a hemocytometer. The effects of ET-1 on c-myc and c-fos were evaluated using Northern blot analysis. Parametric or nonparametric statistics were used as appropriate.
Addition of ET-1 (100 nM) to serum-starved cultured corporal smooth muscle cells was associated with a nearly 2-fold increase in cell number, as well as 2 to 6-fold increases in c-myc and c-fos levels. Cellular proliferation was inhibited by ET(A)- or ET(B)-receptor subtype blockade with BQ123 (1 microM) or IRL1038 (1 microM), respectively, or blockade of Ca2+ channels with verapamil (10 microM). PE (3 microM) had no detectable effect on smooth muscle proliferation.
Cell proliferation was mediated by activation of the ET(A) and ET(B) receptor subtypes, dependent on transmembrane Ca2+ flux, and correlated with significant increases in c-myc and c-fos mRNA levels. These studies extend previous observations to indicate the potential pleotropic actions of this peptide in the regulation of human corporal smooth muscle physiology in vivo.
胞质钙水平升高会触发平滑肌收缩，而核钙增加则被认为可调节基因表达。内皮素 -1（ET -1）对两者均有影响。这些研究的目的是通过检测ET -1对培养的人阴茎海绵体平滑肌细胞增殖和即刻早期基因（IEG）表达的作用，进一步探究ET -1对阴茎海绵体生理学的重要性。
早期传代（1 - 3代）的平滑肌细胞在培养中生长，并在有无血清的情况下分别暴露于去氧肾上腺素（PE）或ET -1、ET(A)或ET(B)选择性拮抗剂BQ123或IRL1038，或L型钙通道阻滞剂维拉帕米。用血细胞计数器评估细胞增殖。使用Northern印迹分析评估ET -1对c - myc和c - fos的影响。根据情况使用参数或非参数统计方法。
向血清饥饿培养的阴茎海绵体平滑肌细胞中添加ET -1（100 nM）会使细胞数量增加近2倍，同时c - myc和c - fos水平增加2至6倍。分别用BQ123（1 μM）或IRL1038（1 μM）阻断ET(A)或ET(B)受体亚型，或用维拉帕米（10 μM）阻断钙通道可抑制细胞增殖。PE（3 μM）对平滑肌增殖无明显影响。
细胞增殖由ET(A)和ET(B)受体亚型的激活介导，依赖跨膜钙通量，并与c - myc和c - fos mRNA水平的显著增加相关。这些研究扩展了先前的观察结果，表明该肽在体内调节人阴茎海绵体平滑肌生理学方面具有潜在的多效性作用。
