RT Journal Article SR Electronic T1 MECHANISM OF THE POSITIVE INOTROPIC ACTION OF PURINE NUCLEOSIDES IN ISOLATED ATRIA JF Journal of Pharmacology and Experimental Therapeutics JO J Pharmacol Exp Ther FD American Society for Pharmacology and Experimental Therapeutics SP 78 OP 82 VO 145 IS 1 A1 Ira Rosenblum A1 A. A. Stein YR 1964 UL http://jpet.aspetjournals.org/content/145/1/78.abstract AB This investigation has shown that a purine nucleoside can possess both positive and negative inotropic properties depending on the dose employed. The positive inotropic property of one such purine nucleoside, guanosine, appears to be mediated through the release of heart catecholamines. The storage sites from which these catecholamines are mobilized would seem to be the same one acted upon by tyramine. Neither the positive nor the negative inotropic effects of guanosine are affected by atropine and appear to be independent of the release of acetylcholine. Study of structural variants of guanosine, including guanine, deoxyguanosine and 6-thio-guanosine indicate that the intact sugar moietyof the purine nucleoside is necessary for greatest cardiac effect. The Williams & Wilkins Comapny