Adenylate cyclase of platelets from spontaneously hypertensive rats: reduction of the inhibition by GTP.
We have compared the effects of Gpp[NH]p on adenylate cyclase activity of platelet membranes in SHR and WKY rats. In the presence of 50 microM forskolin, low concentrations of Gpp[NH]p (0.01 to 0.3 microM) inhibited the enzyme activity in both strains, but the maximal level of inhibition was significantly lower in SHR (- 20%). In the absence of forskolin, 0.1 microM Gpp[NH]p was inhibitory only in WKY and the adenylate cyclase activity was greater in hypertensive rats at this nucleotide concentration. Increasing Gpp[NH]p from 0.1 to 3 microM induced the same increase of enzyme activity in both strains. In SHR, GTP itself induced a lower inhibition of the enzyme stimulated by 50 microM forskolin or 0.1 microM prostaglandin E1. These results suggest that the modulatory effect of the guanine nucleotide inhibitory protein on adenylate cyclase may be reduced in platelets from SHR.
Coquil
J F
JF
INSERM Unité 7, Dept. de Pharmacologie, Hôpital Necker Paris, France.
Brunelle
G
G
D000262:Adenylyl Cyclases / Q000097:blood*; D000818:Animals; D001792:Blood Platelets / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D005576:Colforsin / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000097:blood; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR / Q000097:blood / Q000378:metabolism*; D011919:Rats, Inbred Strains / Q000378:metabolism*; D011921:Rats, Inbred WKY / Q000097:blood / Q000378:metabolism
D005576:Colforsin; D006165:Guanylyl Imidodiphosphate; D004533:Egtazic Acid; D006160:Guanosine Triphosphate; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases