Rat PHI, PHI-GLY and PHV (1-42) stimulate adenylate cyclase in six rat tissue and cell membranes.
PHI and the two C-terminally extended forms PHI-GLY and PHV(1-42) coexist in rat tissues. We compared the relative potency and efficacy of these three PHI forms and of VIP to stimulate adenylate cyclase activity and, when feasible, to occupy VIP receptors in six rat tissue and cell membranes. With the exception of lung membranes, all three PHI forms were markedly less potent than VIP but all were systematically as efficacious. PHI-GLY and PHV(1-42) were never more potent than PHI itself and their relative potencies revealed four spectra, depending on the membrane preparation tested: 1) PHI = PHI-GLY = PHV(1-42) in hepatic, pulmonary and pancreatic membranes; 2) PHI greater than PHV(1-42) = PHI-GLY in membranes from circulating lymphocytes; 3) PHI = PHV(1-42) greater than PHI-GLY in membranes from the thymocyte cell line 51E; and 4) PHI greater than PHI-GLY = PHV(1-42) in anterior pituitary membranes. These results indicate that the two naturally observed C-terminal extensions of rat PHI variously affected peptide potency on 6 rat membrane preparations.
Cauvin
A
A
Department of Biochemistry and Nutrition, Medical School, Université Libre de Bruxelles, Belgium.
Vandermeers-Piret
M C
MC
Vandermeers
A
A
Coussaert
E
E
de Neef
P
P
Robberecht
P
P
Christophe
J
J
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism*; D009928:Organ Specificity; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D010451:Peptide PHI / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology*; D011498:Protein Precursors / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D011964:Receptors, Gastrointestinal Hormone / Q000378:metabolism; D018005:Receptors, Vasoactive Intestinal Peptide; D015290:Second Messenger Systems / Q000187:drug effects; D012633:Secretin / Q000378:metabolism; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism / Q000494:pharmacology*
D008565:Membrane Proteins; D010446:Peptide Fragments; D010451:Peptide PHI; D011498:Protein Precursors; D011964:Receptors, Gastrointestinal Hormone; D018005:Receptors, Vasoactive Intestinal Peptide; C053900:peptide histidine valine 42; C060707:peptide PHI-(1-27)-glycine; D012633:Secretin; D014660:Vasoactive Intestinal Peptide; D000262:Adenylyl Cyclases