Abstract
Platelet-activating factor (PAF) is a highly potent stimulator of the secretion of cortisol and corticosterone. We previously reported that PAF-receptor antibody recognized by western blot an about 38 kDa protein of the guinea pig adrenal gland. PAF-receptor immunoreactivity was localized in zona glomerulosa cells of guinea pig and human. Zona fasciculata and reticularis showed no immunoreactivity. In the present study, we studied the role of PAF on aldosterone secretion from perfused adrenal gland and dispersed adrenocortical cells. 1) Adrenal glands of the guinea pig were perfused with Krebs Ringer bicarbonate glucose solution equilibrated with 95%O2-5%CO2. The administration of 100nM PAF significantly stimulated the secretion of aldosterone. The concurrent administration of 1nM angiotensin II (ANG II) with 1 nM PAF significantly inhibited the secretion of aldosterone to ANG II. 2) Dispersed adrenocortical cells were prepared using collagenase (10U/ml) and trypsin (10U/ml). Incubation of cells and effectors was carried out with shaking for 90 min under an atmosphere of 95%O2-5%CO2. The response to PAF increased significantly at 10 nM. The response to PAF at 100 -1000nM declined as compared with that at 10 nM. When concurrent applied with 1nM ANG II, 0.01-100nM PAF attenuated the ANG II-induced increase in aldosterone secretion. These results implicate that in adrenal glands of the guinea pig, PAF regulates the cortisol and aldosterone secretion via endogenous PAF receptor-mediated mechanism. [Jpn J Physiol 55 Suppl:S210 (2005)]
