Comparison of the role of sarcoplasmic reticulum Ca2+ pump of esophageal striated musculature of SHRSP and WKY

• Published in: Japanese Journal of Pharmacology Vol. 73; no. suppl.1; p. 221
• Main Authors: Sckicuchi, Fumiko, Nakazawa, Yumi, Matsuda, Kyoko, Shimamura, Keiichi, Sunano, Satoru
• Format: Journal Article
• Language: English
• Published: The Japanese Pharmacological Society 1997
• ISSN: 0021-5198; 1347-3506
• DOI: 10.1016/S0021-5198(19)45386-9

It is known that Ca2+ handling of not only vascular smooth muscle but also other tissues is altered in the preparations from spontaneously hypertensive rats (SHR), when compared with that of respective preparations from Wistar Kyoto rats (WKY). In this study, the role of sarcoplasmic reticulum Ca^2+ pump of esophageal striated musculature from stroke-prone SHR (SHRSP) and normotensive WKY was compared. The esophageal striated musculature from both WKY and SHRSP showed a phasic contraction induced by K^+ 80 mM Tyrodes solution (K80). The contraction was deteriorated by repetitive addition of K80. The rate of the deterioration was more marked in preparations from SHRSP. Electrical field stimulation (EFS) induced a twitch contraction in both preparations. The twitch contraction was deteriorated by repetitive EFS. The rate of the deterioration was more marked in preparations from SHRSP. Cyclopiazonic acid (CPA, 10μM), a specific inhibitor of sarcoplasmic reticulum Ca^2+ -ATPase,induced a tonic contraction in preparations only from WKY. CPA caused a tonic increase in intracellular free Ca^+ concentration ([Ca^2+ ]_i ) in preparations both from WKY and SHRSP, however. The increased level was significantly higher in preparations from WKY. These results indicate that sarcoplasmic reticulum Ca^2+ -ATPase activity of esophageal striated musculature from SHRSP is lower than that of preparations from WKY.