I. Goldenberg et al., Angiotensin II-induced apoptosis in rat cardiomyocyte culture: a possible role of AT(1) and AT(2) receptors, J HYPERTENS, 19(9), 2001, pp. 1681-1689
Citations number
37
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Objectives To investigate the mechanism of angiotensin II-induced apoptosis
in cultured cardiomyocytes by determining which receptor subtype is involv
ed, and what is the relationship between intracellular Ca2+ changes and apo
ptosis.
Design and methods Neonatal rat cardiomyocytes were pretreated with either
the AT(1) antagonist irbesartan or the AT(2) antagonist PD123319 before exp
osure to angiotensin Il. Apoptotis was evaluated using morphological techni
que, staining nuclei by Feulgen and Hoechst methods followed by image analy
sis and by in situ terminal deoxynucleotidyl transferase nick-end (TUNEL) l
abelling. TUNEL-positive cardiocytes were distinguished from other cells by
double staining with a-sarcomeric actin. Intracellular Ca2+ changes were a
ssessed by indo-1 fluorescence microscopy, and the effect of Ca2+ on angiot
ensin II-induced apoptosis was tested using the calcium channel blocker ver
apamil.
Results Exposure to angiotensin II (110 nmol/l) resulted in cell replicatio
n and a three-fold increase in programmed cell death (P < 0.05). Pretreatme
nt with either irbesartan (an AT(1) receptor antagonist, 100 nmol/l) or PD1
23319 (an AT(2) receptor antagonist, 1 mu mol/l) prevented the angiotensin
II-induced apoptosis, indicating the presence of both AT(1) and AT(2) recep
tors on cardiomyocytes. Exposure of myocytes to angiotensin II caused an im
mediate and dose-dependent increase in the concentration of intracellular f
ree Ca2+ that lasted 40-60 s. The effect was sustained in a Ca2+ free mediu
m. Pretreatment of cells with irbesartan (100 nmol/l) and PD123319 (10 mu m
ol/l) blocked Ca2+ elevation. Pretreatment with verapamil (10 lamol/1) prev
ented angiotensin II-induced apoptosis.
Conclusions Angiotensin II-induced apoptosis in rat cardiomyocytes is media
ted through activation of both AT(1) and AT(2) receptors. The apoptotic mec
hanism is not related to the immediate angiotensin II-induced Ca2+ rise fro
m intracellular stores. However, it is accompanied by cardiomyocyte prolife
ration and requires Ca2+ influx through L-type channel activity. (C) 2001 L
ippincott Williams & Wilkins.