Stereospecificity in some central and circulatory effects of phenylisopropyl-adenosine (PIA).
The effects of l- and d-stereoisomers of phenylisopropyl-adenosine (PIA) were tested on the central nervous and circulatory system. In mice l-PIA in doses of 0.1--0.2 mg/kg i.p. reduced motor activity and muscular coordination, prolonged barbiturate sleeping time and exerted a hypothermic and analgetic effect. In most of these tests even 10--20 times higher doses of d-PIA proved to be ineffective. In isolated guinea-pig heart preparation l-PIA increased the coronary flow, diminished the contraction amplitude and frequency in approximately 1/20 of the doses than did d-PIA. Blood pressure of rats was markedly lowered by l-PIA in doses of 6--15 mug/kg i.v. but not by the same dose of d-PIA. There seems to be stereospecificity for PIA in various tissues and animals in vivo as well as in isolated organs. The l-isomer is usually 10--20 times more active than the d-form. In addition to stereospecificity at receptor sites, differences in lipid solubility of the stereoisomers could explain these findings.
D000241:Adenosine / Q000031:analogs & derivatives*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D002490:Central Nervous System / Q000187:drug effects*; D003326:Coronary Circulation / Q000187:drug effects; D003864:Depression, Chemical; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D050356:Lipid Metabolism; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009048:Motor Skills / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D010424:Pentobarbital / Q000494:pharmacology; D010660:Phenylisopropyladenosine; D051381:Rats; D011930:Reaction Time / Q000187:drug effects; D012890:Sleep / Q000187:drug effects; D013237:Stereoisomerism
D010660:Phenylisopropyladenosine; D010424:Pentobarbital; D000241:Adenosine