Recent evidence indicates that Ca2+ dysregulation is involved in the pathogenesis of isoproterenol (ISP)-induced biochemical toxicity and associated oxidative stress. In this study, we investigated the chemopreventive benefit of M3, a 1,4-dihydropyridine calcium channel blocker, against ISP-induced toxicity in male Wistar rats. Adult rats were divided into eight groups of six rats/group. Groups 1–5 received normal saline (control, 10 mL/kg/day, p.o.), ISP (85 mg/kg/day, s.c.), M3 lower dose (M3LD, 5 mg/kg, p.o.), M3 upper dose (M3UD, 20 mg/kg/day, p.o.), and Nifedipine (NFD, 20 mg/kg/day, p.o.), respectively. Others (groups 6–8) were pretreated with either M3LD, M3UD or NFD one hour before ISP administration. All rats were sacrificed 24 h after the last administration and changes in biochemical, hematological, and antioxidant parameters were assessed. Histologic examination of the heart, liver and kidney was also conducted. ISP elevated (p
