Differential effects of furnidipines' metabolites on reperfusion-induced arrhythmias in rats in vivo

Cardiomyopathy development protection after myocardial infarction in rats: Successful competition for major dihydropyridines' common metabolite against captopril

During the last 25 years angiotensin-converting enzyme inhibitors spectacularly conquered the field of cardiovascular diseases therapy. Nevertheless, lack of new studies concerning side effects associated with their chronic administration seems to be rather confusing. In our previous research, we proved that the main furnidipines' metabolite (M-2) possess multiple cardioprotective actions. Currently, we compared effects of post-infarction long-term oral treatment with M-2 and captopril on hemodynamic parameters and "ischemic cardiomyopathy" development in rats. Myocardial infarction was evoked by permanent left anterior descending coronary artery occlusion for 35 days. Surviving rats were treated with captopril (2 × 25 mg/kg) or M-2 (4 mg/kg) from 6th- 35th day. At 35th day rats' hearts were tested on working heart setup, where following parameters were measured: heart rate, preload pressure, aortic systolic and diastolic pressures, aortic maximum rise and fall, aortic and coronary flow, myocardial oxygen consumption and oximetry in perfusate. Subsequently, heart tissue specimens were assessed during morphological estimation. Captopril caused significant heart rate increase and markedly diminished preload pressure in comparison to M-2. Both drugs evoked essential aortic pressure increase. Aortic flow was significantly decreased after M-2, whereas captopril increased this parameter in comparison to M-2. Both agents caused marked coronary flow increase. Morphologic examination in captopril revealed cardiomyopathic process in 70% of hearts, whereas in M-2 this value reached 30%. Neovascularization of post-infarcted myocardium was visible only after M-2 therapy. Concluding, M-2 presented itself as more attractive agent in long-term post-infarction treatment by preventing cardiomyopathy development, angiogenesis stimulation and preserving cardiac performance.

Dihydropyridines' metabolites-induced early apoptosis after myocardial infarction in rats; new outlook on preclinical study with M-2 and M-3

Our previous studies established cardio-protective effects of furnidipine and its active metabolites called M-2 and M-3. The aim of current research was to compare the effects of single oral pretreatment with 20 mg kg(-1) of M-2 and M-3 on mortality, different forms of arrhythmias, blood pressures parameters and ST-segment changes during occlusion (for 90 min) and reperfusion in the model of myocardial infarction in rats evoked by left anterior descending coronary artery occlusion. Additionally, the development of programmed cell death and biochemical parameters in blood serum were studied at 4th day after infarction. Furnidipines' metabolites effectively reduced mortality index while did not markedly influence on blood pressures parameters, arrhythmias, ST-segment changes as well as biochemical parameters. Intriguingly, programmed cell death study (TUNEL) showed distinct increase in the amount of apoptotic nuclei in post-infarcted myocardium, granulation tissue and what is more in arteriolar walls after M-2 and M-3 application. Moreover, M-2 turned out to be more powerful in stimulation of apoptosis in granulation tissue surrounding infarcted area whereas M-3 presented balanced profile in this matter. Taking into account that programmed cell death plays positive role in post-infarcted heart healing, M-2 presents itself as more attractive agent for oral pretreatment in early stages of ischemia by non-stable individuals due to its more specific action in stimulation repairing processes in granulation tissue as well as in arteriolar walls. While M-2 and M-3 are common metabolites present in degradation pathways of many widely used dihydropyridines in clinic, this key fact put the new outlook on understanding additional mechanism and effects of not only furnidipines' metabolites but also other dihydropyridines.