W. Erdbrugger et al., NOREPINEPHRINE AND NEUROPEPTIDE-Y INCREASE INTRACELLULAR CA2-MUSCLE CELLS( IN CULTURED PORCINE AORTIC SMOOTH), Journal of cardiovascular pharmacology, 22(1), 1993, pp. 97-102
We used the fluorescent Ca2+ indicator Fura-2 in cultured porcine aort
ic smooth muscle cells (PASMC) to study effects of the sympathetic neu
rotransmitters norepinephrine (NE) and neuropeptide Y (NPY) on free in
tracellular Ca2+ (Ca(i)). Both transmitters transiently increased intr
acellular Ca2+ in a concentration-dependent manner. Selective agonists
and antagonists demonstrated that the NE-stimulated Ca(i) increase is
predominantly (if not exclusively) mediated by alpha2-adrenoceptors,
whereas the NPY response appears to be mediated by the peptide YY-inse
nsitive Y3-like receptor subtype. Pretreatment of cells with pertussis
toxin abolished NPY and alpha-adrenoceptor agonist-stimulated intrace
llular Ca2+ elevations (but not those stimulated by angiotensin II) su
ggesting involvement of a G(i)-like G-protein. alpha2-Adrenoceptor-sti
mulated Ca2+ increases resulted from mobilization from intracellular s
tores, whereas Y3-like NPY receptors mobilized Ca2+ from intracellular
stores and also promoted Ca2+ influx.