Stimulation of cortisol production through angiotensin AT2 receptors in bovine fasciculata cells.

ABSTRACT

Bovine fasciculata cells in culture (BAC) express both AT1 and AT2 angiotensin receptors. The role and signaling pathways of this latter receptor are still the subject of debate. We found that in BAC stimulation of cortisol (F) production by angiotensin II (A II) is accounted for by both receptor subtypes. We have investigated the potential AT2 signalling pathways involved in this response. As previously described in other cells, we found this receptor to mediate inhibition of ANP stimulated cGMP production through a phosphodiesterase independent pathway. This phenomenon does however not appear to be involved in cortisol production as this response was not affected by the addition of 8-Br-cGMP or ANP. It was however abolished after down-regulation of PKC by phorbol esters, but not by Gi inhibition with pertussis toxin. Moreover and as opposed to the AT1 mediated response, AT2 receptor stimulation potentiated K+ induced F production. In conclusion, these observations suggest that the AT2 pathway which mediates F production requires intact PKC and might involve a Gi independent stimulation of Ca++ or K+ channels.