The present work tested the hypothesis that short-term(S-T) dietary deficiency of magnesium(Mg)(21 days) in rats would result in the up-regulation of the two major subunits of serine palmitoyl-CoA-transferase, SPT 1 and SPT 2( the rate-limiting enzymes responsible for the de novo biosynthesis of ceramides) in left ventricular(LV) ,right ventricular (RV) and atrial heart muscle and abdominal aortic smooth muscle ,as well as induce a reduction in serum sphingomyelin(SM) concomitant with release of mitochondrial cytochrome c (cyto c) in these tissues. Our data indicate that S-T Mg deficiency(MgD) resulted in up-regulation of SPT 1 and SPT 2 concomitant with a very significant release of cyto c in LV,RV ,atrial ,and abdominal aortic smooth muscle. S-T MgD also produced lowering of serum SM and ionized Mg. The greater the reduction in serum ionized Mg , the greater the up-regulation of SPT 1 and 2 and the more the increase in free cyto c. The data suggest that MgD, most likely, causes biosynthesis of ceramides via two pathways in cardiovascular tissues ,viz, via activation of serine palmitoyl-CoA-transferase and sphingomyelinase ,which lead to apoptotic events via" intrinsic"(present study) and "extrinsic" pathways(previous studies). Low levels of drinking water Mg were cardio-and vascular- protective.
- cardiac muscles
- Copyright © 2009, American Journal of Physiology - Heart and Circulatory Physiology