Beta-adrenergic receptor properties of @entity235 myocardium: effects of chronic XXXX .

@entity3141 @entity3163 @entity18013 @entity235 @entity1920 @entity1188 @entity3044 @entity583
To determine the effects of chronic @entity583 on beta-adrenergic properties of @entity235 myocardium, the hearts of nine mongrel @entity235 were studied 3 weeks after @entity583 . @entity1188 was produced by ligating the left anterior descending coronary artery in five @entity235 and the circumflex artery in four @entity235 . The heart was divided into normal and @entity1188 zones (either anterior or posterior, depending on the vessel ligated) and marginal zones (septal and lateral), each zone being subdivided into epicardial and endocardial portions. Myocardial blood flow (microsphere technique) was markedly reduced in the @entity1188 zone. In eight endocardial @entity1188 samples after left anterior descending ligation, the maximal number (+/- SD) of binding sites assessed by 125I- @entity18013 was 3.9 +/- 1.9 pmol/mg @entity3141 ( @entity3141 ) and was reduced from normal endocardial values (9.7 +/- 9.4 pmol/mg @entity3141 , p less than 0.05). The dissociation constant (Kd), which is a measure of the affinity of the iodinated antagonist for the receptor, did not differ (304 +/- 222 versus 338 +/- 219 pM, p = NS). In the epicardium, the maximal number of beta-adrenergic receptors was also reduced (p less than 0.05), without a change in Kd. In the lateral and septal zones neither the maximal number of binding sites nor Kd values differed from those of normal endocardium. In nine endocardial @entity1188 zones, @entity3044 -stimulated @entity1920 cyclase activity was reduced compared with control (34,870 +/- 29,430 versus 88,660 +/- 63,640 pmol/mg @entity3141 /30 minutes, p less than 0.01), but the ratio of @entity3044 -stimulated to maximal ( @entity3163 -stimulated) @entity1920 cyclase activity was unchanged between normal and @entity1188 zones.(ABSTRACT TRUNCATED AT 250 WORDS)
