Low molecular weight G-proteins of rho-family mediate relaxations to bradykinin in porcine coronary arteries.
AIM
To determine whether or not low molecular G-proteins are involved in the endothelium-dependent relaxations to bradykinin.


METHODS
The effects of botulinum ADP-ribosyltranferase C3 were studied in porcine coronary arteries and endothelial cells.


RESULTS
Incubation of membrane fractions isolated from endothelial cells with the enzyme and 32P-NAD resulted in the ribosylation of the proteins with molecular weight of 24-25 kDa. Radio labelling of these proteins was suppressed in the presence of guanosine 5'-O-(3-thiotriphosphate) (GTP-gammaS), a hydrolysis-resistant analog of GTP. In the isolated arteries, ADP-ribosyltransferase C3 attenuated the relaxations to bradykinin during contractions with prostaglandin F2alpha in the presence of tween 80 (non ionic detergent), but not in the absence of tween 80.


CONCLUSION
Low molecular weight G-proteins of the Rho family contribute to the mechanism of relaxation induced by bradykinin.