Basal and stimulated angiotensin II-induced cytosolic free calcium in adult rat cardiomyocytes and fibroblasts after volume overload

Fareh, J., Touyz, R.M. , Thibault, G. and Schiffrin, E.L. (1995) Basal and stimulated angiotensin II-induced cytosolic free calcium in adult rat cardiomyocytes and fibroblasts after volume overload. Hypertension, 26(6.2), pp. 1149-1153. (doi: 10.1161/​01.HYP.26.6.1149)

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Abstract

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). In conclusion, alterations of intracellular calcium homeostasis in the two predominant cardiac cell types involved in myocardial growth and fibrosis, cardiomyocytes and fibroblasts, respectively, may contribute to the physiopathology of heart failure in adult rats. Ang II signaling through the intracellular calcium transduction pathway in a cell-specific manner may play an important role in cardiac hypertrophy.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Touyz, Professor Rhian
Authors: Fareh, J., Touyz, R.M., Thibault, G., and Schiffrin, E.L.
College/School:College of Medical Veterinary and Life Sciences > Institute of Cardiovascular and Medical Sciences
Journal Name:Hypertension
Publisher:American Heart Association
ISSN:0194-911X

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