Ca2+-dependent regulation of rat caudate nucleus adenylate cyclase and effects on the response to dopamine

M. T. Piascik, M. F. Piascik, R. J. Hitzemann, J. D. Potter

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

The Ca2+ dependence of rat caudate nucleus microsomal adenylate cyclase [ATP pyrophosphate-lyase (cyclizing) EC 4.6.1.1] was determined and compared with that of cortical microsomes. Both cyclase preparations exhibited a biphasic response to Ca2+ with no differences in the free Ca2+ concentrations required to stimulate (one-half maximum = 0.19 μM cortex; 0.2 μM caudate) and inhibit (one-half maximum = 1 μM cortex; 0.9 μM caudate) each cyclase system. Whereas the cortical activity was stimulated 7-fold by Ca2+, the caudate activity exhibited only a 2-fold Ca2+-induced enhancement of basal cyclase. This relative insensitivity of caudate adenylate cyclase is not due to the selective loss of calmodulin. Ca2+ concentrations (0.03-0.5 μM) which stimulate the cyclase and the addition of large excesses of calmodulin had no effect on the ED50 of dopamine. The abilities of Ca2+ and dopamine to stimulate caudate adenylate cyclase activity were additive over the concentration range of 0.03-0.5 μM Ca2+. Ca2+ concentrations (> 0.5 μM) which inhibit adenylate cyclase activity abolished the stimulatory effect of dopamine. Therefore, it is suggested that Ca2+ and dopamine, in a coordinated manner, can modulate the response of caudate adenylate cyclase.

Original languageEnglish (US)
Pages (from-to)319-325
Number of pages7
JournalMolecular pharmacology
Volume20
Issue number2
StatePublished - Jan 1 1981

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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