Intracellular free Ca2+ movements in cultured cardiac myocytes as shown by rapid scanning confocal microscopy.
Two-dimensional images of intracellular free Ca2+ movements in cultured cardiac myocytes were obtained at 33-ms intervals with a Ca(2+)-sensitive fluorescence probe, fluo-3, and a rapid scanning confocal laser microscope, a prototype of Nikon RCM8000. The cells used were isolated from the ventricular myocardium of neonatal mice, cultured for approximately 72 h and loaded with fluo-3. One type of cytoplasmic Ca2+ movement observed was a simultaneous increase in [Ca2+] throughout the cytoplasm, termed a "spike"; another type was a local increase in [Ca2+] propagating in the cytoplasm, termed a "wave." Cells with either spike or wave or both types of movements were observed. Tetrodotoxin (TTX) 10(-5) M, nicardipine 10(-6) M, and increased extracellular potassium concentration (40 mM) selectively inhibited spike, and ryanodine 10(-6) M and cyclopiazonic acid (CPA) 3 x 10(-6) M selectively inhibited wave. These results indicate that spike was triggered by depolarization-induced Ca2+ influx across the sarcolemma, whereas wave was a propagating local increase in Ca2+ due to Ca2+ release from the sarcoplasmic reticulum (SR). On spike, nuclear [Ca2+] was shown to increase and decrease synchronously with cytoplasmic [Ca2+], with a delay and slower time course.
Tanaka
H
H
Department of Pharmacology, Toho University School of Pharmaceutical Sciences, Chiba, Japan.
Kawanishi
T
T
Matsuda
T
T
Takahashi
M
M
Shigenobu
K
K
D000814:Aniline Compounds; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002478:Cells, Cultured; D005456:Fluorescent Dyes; D006321:Heart / Q000187:drug effects; D007211:Indoles / Q000494:pharmacology; D051379:Mice; D018613:Microscopy, Confocal; D009206:Myocardium / Q000378:metabolism*; D012433:Ryanodine / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014966:Xanthenes
D000814:Aniline Compounds; D005456:Fluorescent Dyes; D007211:Indoles; D014966:Xanthenes; D012433:Ryanodine; C059715:Fluo-3; D013779:Tetrodotoxin; D000252:Calcium-Transporting ATPases; D002118:Calcium; C000543:cyclopiazonic acid