Vasoactive intestinal peptide (VIP) stimulates [Ca2+]i and cyclic AMP in CHO cells expressing Gα16

The stimulatory effect of vasoactive intestinal peptide (VIP) and analogues on [Ca2+](i) has been investigated in Chinese hamster ovary (CHO) cells stably transfected with the reporter gene aequorin, and expressing either the human VPAC(1) or VPAC(2) receptor in absence or in presence of the G(alpha 16). In cells that were not transfected with G(alpha 16) and expressed a similar density of receptors, the VIP induced [Ca2+](i) increase was higher in VPAC(1) than in VPAC(2) receptor expressing cells. In aequorin/G(alpha 16) cotransfected cells, the VIP-induced response was higher, reaching 70 to 80% of the maximal calcium response, obtained after digitonin treatment, in response to both VPAC(1) and VPAC(2) receptor stimulation. The results suggest that in hematopoietic cells, which express both VIP receptors and G(alpha 16), the signalling pathway of VIP could be mediated through both cyclic AMP and [Ca2+](i) increase. (C) 2001 Harcourt Publishers Ltd.