Correlation of changes in cardiac calcium channels with hemodynamics in Syrian hamster cardiomyopathy and heart failure

Abstract

We compared hemodynamics with [ 3H]nitrendipine (calcium channel) binding to cardiac membranes from Bio 14.6 cardiomyopathic Syrian hamsters at 4 and 10 months with their F 1B controls. A 50% increase in the number (B max) of nitrendipine binding sites (calcium channels) was seen only in the 4 month old myopathic vs controls (B max = 4±11 vs 309±10 fmol/mg prot with no change in affinity (K D) (K D = .65±12 vs .75±14nM), while no differences in B max or K D were seen at 10 months (B max = 375±9 vs 362±7 fmol/mg prot/K D = .82±18 vs .89±17 nM) myopathic vs control respectively. Hemodynamic studies revealed no significant differences in cardiac output, cardiac index, stroke volume, heart rate, mean arterial pressure, peripheral resistance, body weight, heart weight at 4 months, but a significant decrease in peripheral resistance (1120±360 vs 2080±240) increase in body weight (118±2 vs 94±2 grams) and heart weight (97±5 vs 78±2gms/100gms body weight) in 10 month myopathic vs control animals. We conclude that the onset of cardiomyopathy at 4 months is associated with a selective increase in calcium channel binding sites and heart failure at 10 months is associated with a relative decrease in these sites.