Basal and angiotensin II-induced cytosolic free calcium in adult rat cardiomyocytes and fibroblasts after volume overload.
This study investigates basal and angiotensin II (Ang II)-induced [Ca2+]i concentrations in cells from hearts of rats that have undergone cardiac hypertrophy due to volume overload. [Ca2+]i measurements assessed by digital imaging using fura 2 methodology were performed on isolated ventricular cardiomyocytes and fibroblasts from adult rat hearts with a 4-week aortocaval shunt. Long-term aortocaval shunt induced a significant increase in atrial (72%) and ventricular (41%) weights and a large elevation in plasma atrial natriuretic peptide-(1-98) concentration (160%). For adult cardiomyocytes [Ca2+]i measurements are reported as diastolic (average of the lowest points) and systolic intracellular Ca2+ values (average of the maximum points corresponding to the diastolic points) over a 30-second time interval. Basal diastolic [Ca2+]i (99 +/- 4.1 nmol/L for experimental cells versus 90 +/- 4.8 for control cells) was not altered, whereas basal systolic [Ca2+]i was significantly greater in ventricular cardiomyocytes from overload hearts (155 +/- 2.3 versus 129 +/- 4.4 nmol/L for control cells, P < .05). Ang II increased intracellular Ca2+ spike frequency in a concentration-dependent manner in cardiomyocytes from control and overload myocardium. Basal and Ang II-induced intracellular Ca2+ spike frequencies were not modified in cardiomyocytes from hypertrophied hearts. Basal [Ca2+]i in ventricular fibroblasts from overload myocardium was significantly increased (128 +/- 5.1 nmol/L for fibroblasts from hypertrophied hearts versus 104 +/- 3.5 for control cells, P < .05). Ang II-induced [Ca2+]i was lower in fibroblasts from overload myocardium (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)
D000704:Analysis of Variance; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000097:blood; D002118:Calcium / Q000378:metabolism*; D002306:Cardiac Volume; D006332:Cardiomegaly / Q000378:metabolism* / Q000503:physiopathology; D002478:Cells, Cultured / Q000378:metabolism; D003470:Culture Media; D003600:Cytosol / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000166:cytology* / Q000378:metabolism*; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D003470:Culture Media; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D009320:Atrial Natriuretic Factor; D002118:Calcium