Aging Selectively Attenuates L‐Type Calcium Currents in Resistance Coronary Arteries

Abstract

The current density of L‐type voltage‐gated calcium (L‐VGC) channels was reported to be inversely proportional to the diameter of coronary arteries. Since aging is a major risk factor for coronary artery disease, we investigated if the above relationship is altered with aging. Smooth muscle cells were isolated from coronary arteries of young (3‐4 months) and old (22‐26 months) male F344 rats. Whole‐cell L‐VGC currents were recorded using 10 mM Ba2+ as charge carrier from small (˂100µm) and large (250 to 400 µm) diameter arteries. Student's t‐test was used to compare peak inward current densities (pA/pF; mean± S.E.M) between young and old arteries of similar size and the 2‐way ANOVA was used to compare all four groups (P<0.05). In large arteries, current densities were not significantly different between old (‐5.44 ± 0.92; n=13) and young (‐4.33 ± 0.81, n=13) rats. In small arteries, current densities from old (‐3.66 ± 0.41; n=36) were reduced by 2.4 fold compared to those from young rats (‐8.8 ± 0.88; n=27); with similar V0.5 for both activation and inactivation voltages. Current densities recorded from large arteries of young and old rats and from small arteries of old rats were not significantly different. However, current densities recorded from small arteries of young rats were significantly higher than those from the other three groups. L‐type current density of small resistance arteries of young rats is significantly higher than in large arteries. This inverse diameter‐current density relationship is lost with aging. We conclude that aging selectively affects the density of L‐VGC currents of small resistance coronary arteries.This work is funded by The Research Council of Oman