Comparison of responses to pituitary adenylate cyclase activating peptides 38 and 27 in the pulmonary vascular bed of the cat.
Responses to pituitary adenylate cyclase activating polypeptide (PACAP)-38 were investigated and compared with responses to PACAP-27 and vasoactive intestinal polypeptide (VIP) in the pulmonary vascular bed of the intact-chest cat under constant flow conditions. Under low resting tone baseline conditions, injections of PACAP-38 had little or no effect on lobar arterial pressure; however, when tone in the pulmonary vascular bed was raised to a high steady level (35-40 mm Hg) with U46619, intralobar injections of PACAP-38 caused dose-related decreases in lobar arterial pressure without altering left atrial pressure. The peptide induced biphasic changes in systemic arterial pressure. PACAP-38 was more potent than VIP in decreasing lobar arterial pressure, and both peptides were significantly less potent than PACAP-27 in dilating the pulmonary vascular bed. The present data show that PACAP-38 has significant vasodilator activity in the pulmonary vascular bed of the cat, and that the 27 amino acid form of the peptide is approximately 3-fold more potent than PACAP-38.
Cheng
D Y
DY
Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112.
McMahon
T J
TJ
Dewitt
B J
BJ
Carroll
G C
GC
Lee
S S
SS
Murphy
W A
WA
Bitar
K G
KG
Coy
D H
DH
Kadowitz
P J
PJ
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002415:Cats; D005260:Female; D008297:Male; D009479:Neuropeptides / Q000494:pharmacology*; D018377:Neurotransmitter Agents / Q000494:pharmacology*; D010477:Perfusion; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D011667:Pulmonary Veins / Q000187:drug effects*; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology
D009479:Neuropeptides; D018377:Neurotransmitter Agents; D051219:Pituitary Adenylate Cyclase-Activating Polypeptide; D014660:Vasoactive Intestinal Peptide