[The effects of glucose and insulin upon functional recovery in the rat heart preserved by continuous perfusion with St. Thomas' Hospital cardioplegic solution].

UNLABELLED: The aim of this study was to determine the effect of the continuous perfusion with Krebs-Henseleit bicarbonate buffer (KHBB) solution or St. Thomas' Hospital cardioplegic solution (ST solution) containing glucose and insulin upon the post-preservation recovery in the isolated rat heart. METHODS: Hearts from male Wistar rats (n = 6/group) were subjected to working perfusion with KHBB solution for measurement of cardiac function. They were continuously perfused (1) with KHBB solution or ST solution for 12 hours at 20 degrees C, (2) with ST solution for 12 hours at 37 degrees C, 20 degrees C or 4 degrees C, (3) with ST solution or ST solution containing glucose (9 mmol/L) for 12 hours at 20 degrees C or 4 degrees C, and (4) with ST solution containing glucose (9 mmol/L) or ST solution containing glucose (9 mmol/L) and insulin (10 U/L solution) for 20 hours at 20 degrees C. This was followed by 15 min of Langendorff perfusion and 20 min of working perfusion with KHBB solution. During the second working perfusion after preservation, cardiac function was measured again. RESULTS: (1) Percent recoveries of cardiac output (%CO) preserved with KHBB and ST solution were 44.9 +/- 4.0 and 57.7 +/- 3.8%, respectively (p < 0.05). (2) %CO after preservation with ST solution at 37, 20, 4 degrees C were 0*, 57.7 +/- 3.8 and 74.4 +/- 2.2*%, respectively (*p < 0.05 vs the 20 degrees C group). (3) At 20 degrees C, glucose addition to ST solution increased %CO to 76.5 +/- 2.4% from 57.7 +/- 3.8% in glucose-free ST solution group (p < 0.05). However, at 4 degrees C, glucose addition to ST solution was rather harmful and decreased %CO to 61.4 +/- 2.8% from 74.4 +/- 2.2 in glucose-free ST solution group (p < 0.05). (4) The addition of insulin to the glucose-containing ST solution resulted in a significant increase in %CO from 24.6 +/- 4.0% in the insulin-free solution to 69.2 +/- 2.0%. CONCLUSIONS: Our results indicate that 1) ST solution might be better than KHBB solution for a continuous perfusion medium of myocardial preservation, and 2) at 20 degrees C, the addition of glucose and insulin to the ST solution could be beneficial for the continuous infusion as a method of preservation, however, at 4 degrees C, these addition might be harmful, suggesting the temperature dependence in the utility of energy substrate.