Effects of Oxodipine and Nitrendipine on the Size of Experimental Myocardial Infarct in the Rat

Abstract

The protective effect of either oxodipine or nitrendipine (4 mg/kg/twice daily, orally), two dihydropyridines exhibiting calcium channel-blocking properties, against induced infarct-like lesions was examined. Experimental myocardial infarct-like lesions were induced in rats by subcutaneous injection of isoproterenol (0.5 mg/kg). The lesions were mainly located in subendocardial areas of the free wall of the left ventricle, and were intramural at the apex and ventricular septum. Pretreatment with oxodipine significantly reduced the infarct size in the apical and basal myocardium (P < 0.05). Possible explanations for the lack of effect of nitrendipine pretreatment are discussed.

Ultrastructural Evidence of the Protective Effect of Na+/H+ Exchange Inhibition on the in vitro Damage Induced by Ischaemia Reperfusion in the Interventricular Septum of the Rabbit Heart

“…Also, experimental ischaemia and reperfusion exhibited alterations similar to those observed in other in vivo models (Jennings & Reimer 1981;Pérez-Cao et al 1989& 1994. The main cell alterations involved in ischaemic injury to the myocardium were present.…”

“…The significant reduction in myocardial lesions with dimethylamiloride, from a score of grade 4 to score of grade 1-2, and similar to that obtained with calciumchannel blockers (Perez-Cao et al 1989& 1994, indicates that dimethylamiloride had important mitochondrial protection abilities and may induce reduction in intracellular oedema. …”

“…The main cell alterations involved in ischaemic injury to the myocardium were present. Myocardial ischaemia usually result in intracellular oedema, accumulation of lipid droplets, appearance of contracted bands, severe disruption of myofibrils, both swelling and fragmentation of mitochondria, glycogen granules loss, condensation of nuclear chromatin and karyolysis (Pérez-Cao et al 1994). All these results led us to propose a modified table of progressive score for the alterations depending on the severity of lesions (see table 1).…”

“…Morphometrical and ultrastructural studies have clearly demonstrated that pharmacological interventions can significantly reduce the extent of myocardial necrosis, but also the characteristics of cell lesions (Pérez-Cao et al 1989& 1994. Therefore, ultrastructural changes in cardiac myocytes submitted to ischaemic models could clearly help to define the functional situation of the cardiac muscle (Pérez-Cao et al 1994).…”

“…Morphometrical and ultrastructural studies have clearly demonstrated that pharmacological interventions can significantly reduce the extent of myocardial necrosis, but also the characteristics of cell lesions (Pérez-Cao et al 1989& 1994. Therefore, ultrastructural changes in cardiac myocytes submitted to ischaemic models could clearly help to define the functional situation of the cardiac muscle (Pérez-Cao et al 1994). Thus, the use of a revised version of the major ultrastructural criteria of myocardial alterations might help classify and compare different models of ischaemia, both in vivo and in vitro, but also to compare different treatments apparently acting on different cell level or step of lesions.…”