Na+/Ca2+ exchange in isolated smooth muscle cells demonstrated by the fluorescent calcium indicator fura-2.
Fura-2, a novel fluorescent indicator of cytoplasmic calcium concentrations ([Ca2+i]), was 'loaded' into smooth muscle cells isolated from guinea pig taenia coli. Resting cells maintained a stable [Ca2+i] of 107 +/- 26 nM (n = 13), which could be perturbed with ionomycin. [Ca2+i] was elevated by stimulation of the cells with carbachol or 50 mM KCl. Reduction of the plasmalemmal Na+ concentration gradient by inhibition of the Na+/K+-ATPase with ouabain markedly elevated [Ca2+i]; this elevation was dependent on extracellular Ca2+. [Ca2+i] was also increased by replacement of the extracellular Na+ with an organic cation.
D000818:Animals; D001572:Benzofurans; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D004987:Ethers / Q000494:pharmacology; D005456:Fluorescent Dyes; D016257:Fura-2; D006168:Guinea Pigs; D015759:Ionomycin; D008297:Male; D009130:Muscle, Smooth / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D012508:Sarcolemma / Q000502:physiology; D012964:Sodium / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D001572:Benzofurans; D004987:Ethers; D005456:Fluorescent Dyes; D015759:Ionomycin; D011189:Potassium Chloride; D002217:Carbachol; D012964:Sodium; D002118:Calcium; D016257:Fura-2