AJP - Cell Physiology, Vol 272, Issue 4 C1144-C1150, Copyright © 1997 by American Physiological Society

ARTICLES

Myosin isoform expression and force generation in cultured resistance arteries

K. Ishibashi and R. D. Bukoski
Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-1065, USA.

Organ culture of mesenteric resistance arteries results in a loss of force-generating ability, which is prevented by 1alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3]. We have tested the hypothesis that the culture-induced decrease in active stress is associated with altered myosin isoform expression. Rat mesenteric resistance arteries were studied immediately (fresh) or after incubation at 37 degrees C for 48 h in culture medium (control), with 300 pg/ml 1,25(OH)2D3, or with 5 microg/ml insulin. Isometric force was measured by myography; myosin heavy chain (MHC) and regulatory myosin light chain isoform (MLC) contents were determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Maximal active stress to 100 mM K+ (mN/mm2) was greater for fresh (147.8 +/- 4.9) than control (109.2 +/- 4.6, P = 0.001) or insulin (79.6 +/- 8.6, P < 0.001) but not 1,25(OH)2D3 (137.4 +/- 9.5, P = 0.197). Organ culture did not alter MLC or MHC smooth muscle (SM)-1 isoform content. MHC SM-2 content (nmol/mg protein) was greater in fresh (0.038 +/- 0.003) than control (0.026 +/- 0.003, P = 0.012) and insulin (0.027 +/- 0.002, P = 0.018) but not 1,25(OH)2D3 (0.036 +/- 0.003, P = 0.693); nonmuscle MHC (NMM) was observed in insulin. The maximal active stress response to K+ significantly correlated with SM-2 MHC isoform content (r2 = 0.483, P < 0.001). We conclude that 1) arterial organ culture alters MHC isoform content, 2) SM-2 MHC isoform content positively correlates with active stress generation, 3) 1,25(OH)2D3 maintains force-generating capacity by preventing the shift of MHC isoform expression, and 4) insulin impairs force-generating ability by lowering MHC SM-2 content and stimulating NMM expression.

This article has been cited by other articles:

				S.-S. Bolz, S. Pieperhoff, C. De Wit, and U. Pohl Intact endothelial and smooth muscle function in small resistance arteries after 48 h in vessel culture Am J Physiol Heart Circ Physiol, September 1, 2000; 279(3): H1434 - H1439. [Abstract] [Full Text] [PDF]

				A. Lindqvist, I. Nordstrom, U. Malmqvist, P. Nordenfelt, and P. Hellstrand Long-term effects of Ca2+ on structure and contractility of vascular smooth muscle Am J Physiol Cell Physiol, July 1, 1999; 277(1): C64 - C73. [Abstract] [Full Text] [PDF]