Enhancement of low coronary reflow improves postischemic myocardial function.

The effect of reperfusion coronary vasodilatation on postischemic myocardial mechanical function has been investigated in the isolated working rat heart. After a working period to assess control function, all the hearts were subjected to a single infusion (10 ml) of St. Thomas' Hospital cardioplegic solution No. 1 at 4 degrees C and were kept immersed in the same solution for 4 hours at 4 degrees C. Then hearts (six in each group) were initially reperfused at 37 degrees C for 10 minutes, either with ordinary reperfusate (Krebs-Henseleit bicarbonate buffer) or with reperfusate containing additional coronary dilator. After this period, all hearts were subjected to a further 5 minutes of ordinary reperfusate before being put back into the working mode to assess functional recovery. Mean reperfusion coronary flows and the steady coronary flow measured after 10 minutes of reperfusion in ml/min +/- SEM were--Krebs (control): 17.4 +/- 0.39 and 13.4 +/- 0.40; adenosine (3.75 mumol/L): 19.9 +/- 0.6 and 16.7 +/- 0.8; papaverine (0.05 mmol/L): 21.8 +/- 2.3 and 17.3 +/- 1.8; dipyridamole (2 mmol/L): 20.7 +/- 1.7 and 17.9 +/- 1.0; nitroglycerin (15 mg/L): 20.5 +/- 0.45 and 19.9 +/- 1.4; diltiazem (0.05 mmol/L): 19.6 +/- 2.98 and 17.7 +/- 1.8; calcitonin gene-related peptide (0.03 mmol/L): 20.8 +/- 0.69 and 18.0 +/- 1.3; 5-hydroxytryptamine (0.01 mmol/L): 19.2 +/- 0.53 and 16.9 +/- 0.80. Mean postischemic recovery of cardiac output, peak aortic pressure, and differentiation of pressure were expressed as percent of preischemic control +/- SEM were--Krebs: 54.1 +/- 2.8, 69.1 +/- 2.8, and 53.9 +/- 3.0; adenosine: 78.0 +/- 5.6, 89.5 +/- 2.9, and 69.1 +/- 1.9; papaverine: 81.8 +/- 3.9, 91.8 +/- 3.1, and 71.0 +/- 4.1; dipyrdamole: 67.3 +/- 3.3, 84.3 +/- 2.3, and 75.0 +/- 2.7; nitroglycerin: 83.1 +/- 4.8, 79.7 +/- 2.7, and 69.0 +/- 0.5; diltiazem: 76.5 +/- 3.7, 85.9 +/- 2.9, and 73.3 +/- 1.7; calcitonin gene-related peptide: 79.5 +/- 3.6, 90.0 +/- 4.9, and 75.4 +/- 3.9; 5-hydroxytryptamine: 71.6 +/- 3.2, 85.5 +/- 3.5, and 67.9 +/- 4.8. There was a positive correlation between mean reperfusion coronary flow, steady coronary flow, and postischemic recovery of cardiac output, peak aortic pressure, and differentiation of pressure. Mean reperfusion coronary flow, steady coronary flow, and postischemic recovery of cardiac output, peak aortic pressure, and differentiation of pressure were significantly greater in groups reperfused with vasodilators (p < 0.05) compared with control values.(ABSTRACT TRUNCATED AT 400 WORDS)