Effects of low concentration of dihydroouabain on intracellular calcium in guinea pig ventricular myocytes.
The effects of low concentration of dihydroouabain (DHO) on intracellular calcium concentration ([Ca(2+)](i)) were investigated in guinea pig ventricular myocytes. [Ca(2+)](i) was detected by confocal microscopy and represented by fluorescent intensity. DHO (1 fmol/L~1 mmol/L) increased [Ca(2+)](i), especially at 10 pmol/L. Nisoldipine, egtazic acid, or tetrodotoxin partially inhibited the effect of 10 pmol/L DHO on [Ca(2+)](i). The effects of DHO remained in the absence of extracellular K(+) and Na(+). These results suggest that low concentration of DHO might increase [Ca(2+)](i) via the receptor-operated Ca(2+) channels, TTX-sensitive Na(+) channels or/and triggering of intracellular calcium release; Na(+)/K(+) pump and Na(+)/Ca(2+) exchange seem not involved in the effect of DHO.
Yin
Jing-Xiang
JX
Department of Pharmacology, Institute of Basic Medicine, Hebei Medical University, Shijiazhuang, China.
Wang
Yong-Li
YL
Li
Qing
Q
Shang
Zhong-Lin
ZL
Su
Su-Wen
SW
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006168:Guinea Pigs; D006352:Heart Ventricles / Q000166:cytology; D008297:Male; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010042:Ouabain / Q000031:analogs & derivatives* / Q000494:pharmacology; D018408:Patch-Clamp Techniques
C000977:dihydroouabain; D010042:Ouabain; D002118:Calcium