Steady-state dependence of stress on cross-bridge phosphorylation in the swine carotid media.
Steady-state dependence of stress on cross-bridge phosphorylation in the swine carotid media.
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猪颈动脉中度应激对跨桥磷酸化的稳态依赖性。
DOI：
10.1152/ajpcell.1992.262.6.c1388
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Murphy,RA
中科院分区：
文献类型：
--
作者：
DiBlasi,P;VanRiper,D;Kaiser,R;Rembold,CM;Murphy,RA
猪颈动脉中膜的紧张性收缩的典型特征在于肌浆[Ca 2 +]和跨桥磷酸化的初始瞬变，随后是细胞内[Ca 2 +]和跨桥磷酸化降低的力维持（“闩锁”）。在颈动脉中膜中存在有效的机制来限制稳态肌浆[Ca 2 +]和跨桥磷酸化，使其相对于静息值适度增加，这限制了确定主动应力（力/组织横截面积）对跨桥磷酸化的依赖性的实验尝试。在这项研究中，我们采用的刺激方案，结合有效的收缩激动剂与抑制剂的Ca 2+挤出或螯合，以实现高稳态水平的跨桥磷酸化（高达60%）。跨桥磷酸化从30%增加到60%与应激的显著增加无关，这与Hai和Murphy的预测一致[Am. J.Physiol.254（Cell Physiol.23）：C99-C106，1988]用于颈动脉中膜的四状态跨桥模型。因此，如果磷酸化和去磷酸化连接的横桥（或闩桥）有助于主动应力，则横桥磷酸化可能足以确定血管平滑肌中的力产生。
Tonic contractions of the swine carotid media are typically characterized by initial transients in myoplasmic [Ca2+] and cross-bridge phosphorylation followed by force maintenance with reduced intracellular [Ca2+] and cross-bridge phosphorylation (“latch”). The presence of effective mechanisms in the carotid media to limit steady-state myoplasmic [Ca2+] and cross-bridge phosphorylation to modest increases over resting values has limited experimental attempts to determine the dependence of active stress (force/tissue cross-sectional area) on cross-bridge phosphorylation. In this study, we employed stimulation protocols that combined effective contractile agonists with inhibitors of Ca2+ extrusion or sequestration to achieve high steady-state levels of cross-bridge phosphorylation (up to 60%). Increases in cross-bridge phosphorylation from 30 to 60% were not associated with significant increases in stress in agreement with the predictions of Hai and Murphy [Am. J. Physiol. 254 (Cell Physiol. 23): C99-C106, 1988] four-state cross-bridge model for the carotid media. Thus cross-bridge phosphorylation may suffice to determine force generation in vascular smooth muscle if both phosphorylated and dephosphorylated attached cross bridges (or latch bridges) contribute to active stress.