PHORBOL ESTER-INDUCED CONTRACTIONS OF SWINE CAROTID-ARTERY ARE SUPPORTED BY SLOWLY CYCLING CROSSBRIDGES WHICH ARE NOT DEPENDENT ON CALCIUM OR MYOSIN LIGHT-CHAIN PHOSPHORYLATION

被引:29
作者
FULGINITI, J
SINGER, HA
MORELAND, RS
机构
[1] GRAD HOSP PHILADELPHIA,BOCKUS RES INST,415 S 19TH ST,PHILADELPHIA,PA 19146
[2] GRAD HOSP PHILADELPHIA,DEPT SURG,PHILADELPHIA,PA 19146
[3] GEISINGER MED CLIN,WEIS CTR RES,DANVILLE,PA
关键词
SWINE CAROTID ARTERY; MUSCLE MECHANICS; PROTEIN KINASE-C; CALDESMON; VASCULAR SMOOTH MUSCLE;
D O I
10.1159/000159012
中图分类号
Q4 [生理学];
学科分类号
071003 ;
摘要
This study determined if phorbol ester-induced contraction of vascular smooth muscle requires calcium-dependent myosin light chain (MLC) phosphorylation and, if not, whether the mechanical characteristics of the contraction in terms of stiffness and crossbridge cycling are similar to those during a calcium- and MLC phosphorylation-dependent contraction. Carotid arterial strips were exposed to 1.0 muM phorbol 12,13-dibutyrate (PDBu) in the presence of normal physiological salt solution (PSS) or after calcium depletion in calcium-free PSS and compared with contraction elicited by calcium-containing 110 mM KCl-PSS. PDBu induced maximal stress in both the presence and absence of calcium. While there was a temporal correlation between MLC phosphorylation and shortening velocity during KCl depolarization, shortening velocity was dissociated from MLC phosphorylation during PDBu stimulation. The stress-stiffness relationship was not different during KCl and PDBu stimulation, suggesting similar crossbridge interactions even though MLC phosphorylation levels were significantly different. These results demonstrate that PDBu-induced contraction of the swine carotid artery is not dependent on calcium or MLC phosphorylation. We suggest the possibility that activation of a calcium-independent PKC isoform may result in the expression of an inherent level of actin-activated myosin ATPase activity resulting in the slow development of stress.
引用
收藏
页码:315 / 322
页数:8
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