Vasoactive intestinal peptide in bovine pulmonary artery: localisation, function and receptor autoradiography.
The role of vasoactive intestinal peptide ( VIP) in the control of pulmonary vascular tone was investigated by functional response, immunocytochemical localisation and receptor autoradiography in bovine pulmonary arteries. VIP-immunoreactive nerve fibres were present at the adventitial-medial junction and in the media of the vessels. Exposure of precontracted bovine pulmonary artery segments to VIP in vitro resulted in almost complete (86 +/- 3%; mean +/- s.e.mean) relaxation, the concentration needed for 50% relaxation being 4.47 +/- 0.37 X 10(-9)M. VIP effects did not depend on the presence of intact endothelial cells. The distribution of VIP receptors was studied by autoradiography using [125I]-VIP. A high density of VIP receptors was found in arterial vascular smooth muscle, with a gradient of density from adventitia to luminal surface. There were no receptors on endothelial cells. These data show that VIP is a potent vasodilator of bovine pulmonary arteries, via direct activation of VIP receptors in vascular smooth muscle. VIP-immunoreactive nerves may influence pulmonary vascular tone directly and could, therefore, be important in regulating pulmonary blood flow.[1]References
- Vasoactive intestinal peptide in bovine pulmonary artery: localisation, function and receptor autoradiography. Barnes, P.J., Cadieux, A., Carstairs, J.R., Greenberg, B., Polak, J.M., Rhoden, K. Br. J. Pharmacol. (1986) [Pubmed]
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