Abstract

The effect of pertussis toxin treatment was studied on the inhibitory effect of atrial natriuretic factor (ANF) on adenylate cyclase activity in rat aorta. The incubation of rat aorta washed particles with pertussis toxin and [alpha-32P]NAD resulted in the ADP-ribosylation of a single 40-kDa protein. In addition, pertussis toxin treatment enhanced guanosine 5'-O-(thiotriphosphate) and isoproterenol-stimulated adenylate cyclase activities and attenuated the ANF-mediated inhibition of basal, isoproterenol-, and forskolin-stimulated adenylate cyclase activities. These data suggest that ANF receptors are coupled to adenylate cyclase through inhibitory guanine nucleotide regulatory protein.

Highlights

  • On the presence of guanine nucleotides [13, 15], suggesting that ANF receptors are negatively coupled to the adenylate cyclase system

  • The effect of pertussis toxin treatment was studied cyclase in rat aorta. These data suggest that ANF receptors on theinhibitory effect of atrial natriureticfactor are coupled to adenylate cyclase through inhibitory guanine (ANF) on adenylate cyclase activity in rat aorta

  • The degree of GTPyS activation was much larger, at all the effective concentrations in pertussis toxin (PT)-treated membranes, suggesting that PT interacts with guaninenucleotide regulatory component.Similarresults were obtained, when PT

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Summary

INVOLVEMENT OF INHIBITORY GUANINE NUCLEOTIDE REGULATORY PROTEIN*

On the presence of guanine nucleotides [13, 15], suggesting that ANF receptors are negatively coupled to the adenylate cyclase system. The abbreviations used are: PT, pertussis toxin; ANF, rat syn- treated with PT (treated)or without PT (control) for 30 min at 30 'C thetic atrial natriuretic factor (Arg'o'-Tyr'2s); Gi, inhibitory guanine in the same reaction mixture as described above for ADP-ribosylation nucleotide regulatory protein; SDS, sodium dodecyl sulfate; GTP+, except 1 mM NAD instead of [W~'P]NADwasused. Preincubation of aorta washed particles at 30 'C for 30 min in the absence or presence of PT resultedin a significant loss of enzyme activity whichwas independent of the presence of PT in the incubation medium

RESULTS AND DISCUSSION
GrPyS IpMJ
Adenylate cyclase activity

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