Species differences in susceptibility to ischemic injury and responsiveness to myocardial protection.

Isolated hearts from rabbits, hamsters, ferrets, gerbils, rats, mice and guinea pigs were used to investigate species differences in (i) stability during aerobic perfusion, (ii) susceptibility to ischemic injury and (iii) responsiveness to cardioplegic protection. During 120 minutes of continuous aerobic perfusion, the rate of functional deterioration differed between species. The rabbit was the most stable and the guinea pig the least: the mean +/- SEM of the left ventricular developed pressure falling, after 120 minutes of perfusion, to 82 +/- 4% and 60 +/- 6%, respectively. In studies with 30 minutes of ischemia and 60 minutes of reperfusion, the developed pressure recovered to 72 +/- 2, 71 +/- 2, 65 +/- 3, 64 +/- 2, 58 +/- 3, 50 +/- 8 and 50 +/- 2% of its pre-ischemic value in the rabbit, hamster, ferret, gerbil, rat, mouse and guinea pig, respectively. With 60 minutes of ischemia, the recovery of developed pressure in the guinea pig, rabbit, rat, mouse, hamster, ferret and gerbil was 5 +/- 1, 19 +/- 2, 22 +/- 3, 30 +/- 5, 55 +/- 4, 60 +/- 2 and 45 +/- 5%, respectively. Creatine kinase leakage and changes in tissue metabolite content generally reflected the degree of functional injury. In further studies, groups of 6 hearts were infused for 2 minutes with St. Thomas' Hospital Cardioplegic Solution, then subjected to 30 minutes of ischemia. Cardioplegia improved the recovery of developed pressure in the rabbit, hamster, gerbil, rat and mouse (from 72 +/- 2, 71 +/- 2, 64 +/- 2, 58 +/- 3 and 50 +/- 8% to 82 +/- 3, 103 +/- 3, 84 +/- 4, 77 +/- 2 and 78 +/- 5%, respectively; p less than 0.05 for each species). However, no protection was observed in the ferret and guinea pig (65 +/- 3 and 50 +/- 2% versus 66 +/- 3 and 47 +/- 6%, respectively; p = NS). With cardioplegia, tissue high-energy phosphates increased significantly in all species except the gerbil. Rat and guinea pig hearts were taken for time-response studies (ischemia for 15, 20, 30, 45, 50 and 60 minutes in the rat and 15, 30, 45 and 60 minutes in the guinea pig) with or without cardioplegia. In the rat, cardioplegia improved recovery over an ischemic time-window of 20-45 minutes, but in the guinea pig no improvement was detected. Creatine kinase leakage reflected the patterns of functional recovery. In contrast, high-energy phosphates were preserved better in both species after 30 minutes of ischemia.(ABSTRACT TRUNCATED AT 400 WORDS)