Effects of SC-52458, a new nonpeptide angiotensin II receptor antagonist, on increase in cytoplasmic Ca2+ concentrations and contraction induced by angiotensin II and K(+)-depolarization in guinea-pig taenia coli.
1. The effects of angiotensin (Ang) II receptor antagonist, SC-52458, on peak and plateau components of Ang II-induced contraction were evaluated in the guinea-pig taenia coli. 2. SC-52458 suppressed both the components of and increases in cytoplasmic Ca2+ concentrations, [Ca2+]i, coupled with the contraction by Ang II; tetrodotoxin and atropine did not affect the contractions. 3. SC-52458 inhibited a plateau component of the contraction induced by K(+)-depolarization to some extent, without affecting a peak component. 4. SC-52458 suppressed both the contraction and increase of [Ca2+]i by antagonizing AT1 receptors in the smooth muscle.
Usune
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S
Research Laboratory of Biodynamics, School of Medicine, Fukuoka University, Japan.
Furukawa
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T
D015059:1-Sarcosine-8-Isoleucine Angiotensin II / Q000494:pharmacology; D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D003106:Colon / Q000187:drug effects / Q000378:metabolism; D003593:Cytoplasm / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology; D010276:Parasympatholytics / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology*; D013777:Tetrazoles / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology
D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000959:Antihypertensive Agents; D009467:Neuromuscular Depolarizing Agents; D010276:Parasympatholytics; D011725:Pyridines; D013777:Tetrazoles; C084927:forasartan; D000804:Angiotensin II; D013779:Tetrodotoxin; D001285:Atropine; D015059:1-Sarcosine-8-Isoleucine Angiotensin II; D011188:Potassium; D002118:Calcium