Heterogeneity of pituitary adenylate cyclase-activating polypeptide and vasoactive intestinal polypeptide receptors in rat intrinsic cardiac neurons

The expression of receptors for pituitary adenylate cyclase-activating polypeptide (PACAP) and vasoactive intestinal polypeptide (VIP) was investigated in isolated parasympathetic neurons of neonatal rat intracardiac ganglia using single-cell reverse transcription-polymerase chain reaction. Individual neurons were shown to express multiple isoforms of the PACAP receptor, PAC1, including PAC1-short, -HOP1 and -HOP2 variants, which differ in the region encoding the G protein-binding domain. The PAC1-HOP1 isoform was the predominant species, being expressed at higher levels and in a greater number of cells than other PAC1 variants. In addition to PAC1, intrinsic cardiac neurons express transcripts for the VIP receptors, VPAC1 and VPAC2, with VPAC2 being found in a greater proportion of the neurons. These findings may explain the complex effects of PACAP and VIP on neuroexcitability in mammalian intracardiac ganglia. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.