ISSN:
1573-4919
Keywords:
smooth muscle
;
vascular
;
ATPase
;
calcium
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
Notes:
Abstract Densities of sarcoplasmic reticulum (SR) Ca2+-pump were compared in proximal and distal segments of pig left coronary artery using two biochemical methods: acylphosphate formation and immunoreactivity in Western blots, and a functional assay based on contraction to SR Ca2+-pump inhibitors. In the microsomes prepared from smooth muscle, the level of the 115 kDa SR Ca2+-pump acylphosphate was 7.1 ± 0.3 -fold greater in distal than in proximal segments. Similarly in Western blots using these microsomes, the reactivity of the 115 kDa band to an anti-SR Ca2+-pump antibody was 5.3 ± 0.8 -fold greater in distal than in proximal segments. Endothelium free coronary artery rings contracted to the SR Ca2+-pump inhibitors Cyclopiazonic acid (CPA, EC50 = 0.19 ± 0.06 μM) and thapsigargin (EC50 = 0.0095 ± 0.0035 μM). With 10 μM CPA, the force of contraction per tissue wet weight was 4.2 ± 0.5-fold greater in distal than in proximal rings, and with 1 μM thapsigargin it was 4.0 ± 1.0 -fold greater. The contractions produced by 60 mM KCl were used as a control. In contrast to the CPA and thapsigargin, the force per mg tissue weight produced by 60 mM KCl did not differ significantly between the proximal and distal segments. Thus, the results from the two biochemical methods and those from the contractility data were all consistent with the smooth muscle in the distal segments of the coronary artery containing a higher density of the SR Ca2+-pump than the proximal segments.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00225887
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