Maturational differences in coronary flow and interstitial transudate adenosine during alteration of perfusate oxygenation in isolated rabbit hearts.

This study was designed to investigate effects of perfusate oxygenation and maturation on coronary flow (CF), interstitial transudate adenosine (ITA) and coronary effluent adenosine (CEA) in isolated rabbit hearts. Hearts were paced at a fixed rate and were perfused under constant pressure at two different levels of perfusate oxygenation: baseline (B) (pO2 = 408 +/- 7 mmHg, O2 content = 1.28 +/- 0.03 ml O2/dl) and a lower level (L) (pO2 = 189 +/- 4 mmHg, O2 content = 0.59 +/- 0.02 ml O2/dl). CF was higher in immature (I, age 5 weeks) compared with mature (M, age 12 weeks) hearts at both levels of perfusate oxygenation (9.7 +/- 0.4 vs. 7.7 +/- 0.3 and 12.9 +/- 0.4 vs. 9.2 +/- 0.3 ml/min/g). I hearts had correspondingly higher values for myocardial oxygen consumption (MVO2) (53 +/- 3 vs. 49 +/- 2 and 39 +/- 3 vs. 35 +/- 2 microL O2/min/g), but similar values for venous oxygen tensions (nuO2) (240 +/- 9 vs. 219 +/- 10 and 74 +/- 4 vs. 62 +/- 3 mmHg), compared with M hearts at B and L. Although interstitial transudate adenosine (ITA) concentration was similar in I and M hearts at B (409 +/- 75 vs. 254 +/- 39 nM), it was lower in I than M hearts at L (2500 +/- 770 vs. 4210 +/- 1000 nM).(ABSTRACT TRUNCATED AT 250 WORDS)