| Summary: | CONCLUSIONS our measurementsof agonist.stimulatedhigh-affiniý GTPase activiý and GTftS binding in thedevelopingrat brain cortexhaverevealeda markedlyhigherfunctionalactivity of GTP.binďng proteins in adult (9O{ay.old) than in immaturate(12day.o1d) ťaB.This study further demonsbatesthat RGSI, by contrast to RGSI6, might function as srong regulatorofhigh-afiiniý GTPase activity in this tissue. AC activity is regulatedsimilarly in brain cortex from immaturateand adult rats,but theenzymeactivity is much lower in adultthanin immaturateanimals.As arguedpreviously, the ďfference betweenAc actiúty in thesetwo agegroups is not explicable on the basis of the dwelopmental expressionprofiles of either ACl, ACz, AC4 and AC6 or ďfferent G proteins(Ihnatorrychet a1.,2@2a;Ihnatov.vchetal.,2002b).Itmightbe speculated,however, that the complement of some other types of AC could gg slanged in adulthood. This supposition is supportedby our recent finding of altered characteristicsof [3H]forskolin binding in cerebrocorticalmembranesfrom adult comparedto imÍraturaterats (Stóhr et al., 2005b)-Nevertheless,a possibilitycan not be ruled out thatAC activityin adultrat brain cortex might be perhaps affected by some yet not known negative regulatory factor/mechanism,which is switchedon shortlyaftermaturation. That high-afÍiniý as well...
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