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  • 1
    Electronic Resource
    Electronic Resource
    Angiotensin II contractions in coronary artery (1994)
    Springer
    Molecular and cellular biochemistry 135 (1994), S. 11-19 
    Details
    ISSN: 1573-4919
    Keywords: cardiac ; fluorescence ; cyclopiazonic acid ; thapsigargin ; sarcoplasmic reticulum ; smooth muscle ; vascular
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Pig coronary artery rings denuded of endothelium contract to the vasoactive hormone angiotensin II (Ang II). The nature of Ang II receptors and their Ca2+-pool utilization were examined for contraction of the artery rings and for increase in ultracellular [Ca2+] ([Ca2+]i) in smooth muscle cells cultured from them. Ang II contracted the arteries (EC50=7±4 nM) but with a lower maximal force (1.4±0.25 N/g tissue) than the contraction with 60 mM K+ (6.11±0.63 N/g tissue). In the cultured cells it caused a transient increase in [Ca2+]i with an EC50 value of 11±4 nM. The cells bound Ang II with a dissociation constant (Kd) of 7±2 nM. Based on the effects of the Ang II antagonists saralasin, DuPont 753, dithiothreitol and PD123319, the Ang II receptors responsible for contraction, increase in [Ca2+]i and Ang II binding to coronary artery smooth muscle were of type AT1. The contraction to Ang II was abolished by EGTA but not by nitrendipine. The sarcoplasmic Ca2+ pump inhibitors cyclopiazonic acid (10 μM CPA) and thapsigargin (1 μM) produced contractions of 4.35±0.73 and 2.07±0.54 N/g, respectively. Ang II contractions in the control arteries were nearly abolished upon pretreatment with CPA and thapsigargin. CPA and thapsigargin induced contractions were abolished by exposure to EGTA for 1 h but short exposure of the cells to EGTA only modulated the CPA or thapsigargin induced increase in [Ca2+]i; Ang II induced increase in [Ca2+]i was not inhibited by 1 μM nitrendipine but was reduced significantly by a 30–60 sec exposure to EGTA. CPA and thapsigargin caused an increase in [Ca2+]i even after 30–200 sec exposure to EGTA. Ang II when added after CPA or thapsigargin did not cause a further increase in [Ca2+]i but when added before them it caused an increase in [Ca2+]i and reduced the increase caused by subsequent addition of CPA or thapsigargin. These data are consistent with the concept that Ang II utilizes an intracellular Ca2+-pool which is a small component of the CPA or thapsigargin sensitive Ca2+-pool.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00925957
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  • 2
    Electronic Resource
    Electronic Resource
    Sarcoplasmic reticulum Ca2+-pump density is higher in distal than in proximal segments of porcine left coronary artery (1979)
    Springer
    Molecular and cellular biochemistry 158 (1979), S. 91-95 
    Details
    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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  • 3
    Electronic Resource
    Electronic Resource
    Properties of the sarcoplasmic reticulum Ca2+-pump in coronary artery skinned smooth muscle (1995)
    Springer
    Molecular and cellular biochemistry 151 (1995), S. 149-155 
    Details
    ISSN: 1573-4919
    Keywords: SERCA2 ; ATPase ; calcium ; transport ; vascular
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Pig coronary artery cultured smooth muscle cells were skinned using saponin. In the presence of an ATP-regenerating system and oxalate, the skinned cells showed an ATP-dependent azide insensitive Ca2+-uptake which increased linearly with time for 〉1 h. The Ca2+-uptake occurred with Km values of 0.20±0.03 μM for Ca2+ and 400±34 μM for MgATP2−. Thapsigargin and cyclopiazonic acid inhibited this uptake with IC50 values of 0.13±0.02 and 0.56±0.04 μM, respectively. These properties of SR Ca2+-pump are similar to those reported for membrane fractions isolated from fresh smooth muscle of coronary artery and other arteries. However, optimum pH of the uptake in the skinned cells (6.2) was lower than that reported previously using isolated membranes (6.4–6.8).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01322337
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