Abstract
The vasodilating effects of the post-synaptic, vascular dopamine receptor (DA1) agonist, fenoldopam (Fen) on the systemic and renal vascular beds have been widely investigated. The effect of Fen on the pulmonary vascular bed is not well known. Using an isolated, in situ, salt perfused, isogravimetric rat lung preparation, we devised an experiment in which we infused Fen into the isolated lung during normotensive pulmonary artery pressure (PAP), during prostaglandin (PGF2α) induced pulmonary hypertension, and after DA1 blockade with SCH 23390, during a hypertensive state. Four Sprague-Dawley rats were studied. For all experiments, PAP and LAP were directly measured while flow (Q) was maintained at a constant rate, (Q ≥ 0.03 ml/kg/min). PVR was calculated, PVR = (PAP - LAP)/Q. ΔPAP and ΔPVR for all experimental conditions were evaluated by normal distribution analysis with a null hypothesis stating that PAP=0 and PVR=0. The null hypothesis is rejected at p<0.05. Data are presented as mean ± SD. Fen infused during normotensive PAP caused no significant change in PAP (ΔPAP=−0.05±0.06 mm Hg) and PVR (ΔPVR=−0.001±0.002 r units). During a PGF2α induced pulmonary hypertensive state, infusion of Fen significantly (P≤0.05) decreased PAP (ΔPAP= −1.25±0.5 mm Hg) and PVR (ΔPVR=−0.41±0.028 r units). The DA1 receptor antagonist, SCH 23390, effectively blocked the action of Fen during hypertensive PAP (ΔPAP=−0.08±0.3 mm Hg) and PVR (ΔPVR=−0.003±0.013 r units). Our results suggest that vasodilatory DA1 receptors are present in the pulmonary vascular beds of rats, DA1 induced vasodilation occurs during vasoconstrictive states, and the vasodilatory effect is blocked by DA1 receptor blockade.
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Polak, M., Cause, G., Cassin, S. et al. EVIDENCE FOR VASODILATORY DA1 RECEPTORS IN THE PULMONARY VASCULAR BEDS OF RATS. Pediatr Res 21 (Suppl 4), 240 (1987). https://doi.org/10.1203/00006450-198704010-00440
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DOI: https://doi.org/10.1203/00006450-198704010-00440