MEASUREMENT OF EARLY EVENTS IN SIGNAL-TRANSDUCTION BEYOND RECEPTORS INVOLVING G-PROTEINS FUNCTION IN MONONUCLEAR LEUKOCYTES

G protein function in human mononuclear leucocytes was measured throug h isoproterenol, carbamylcholine and dopamine-enhanced H-3-Gpp(NH)p bi nding. Dopamine and carbamylcholine exerted their effects through D-5 and M(2) receptors, respectively. ADP-ribosylation by bacterial toxins indicates that dopamine and isoproterenol affected G(s), while carbam ylcholine affected G(i). Quantitative G proteins measures were conduct ed through immunoblot analyses with specific polyclonal antibodies aga inst G alpha(s), and G alpha(i) subunits. Simultaneous functional and quantitative measures of G proteins showed significant correlations be tween function and immunoreactivities. Agonist-enhanced guanine nucleo tide exchange is thus suggested as a method for measurement of early e vents in signal transduction beyond receptors in leucocytes, which can potentially serve for detecting alterations in G proteins measures in human disease.