Awumey E M, Pehowich D J
Department of Oral Biology, University of Alberta, Edmonton, Canada.
J Cardiovasc Pharmacol. 1995 Mar;25(3):473-80. doi: 10.1097/00005344-199503000-00019.
The calcium sensitivity of papillary muscles was enhanced at low [Ca2+] in euthyroid rats fed a diet enriched in n-3 fatty acids compared to rats fed diets high in n-6 and saturated (SAT) fatty acids. At the same time, the maximum developed tension was 44% lower in animals fed the n-3 diet compared to those fed the n-6 diet and 62% lower than the rats fed the SAT diet. In hypothyroid animals fed the n-3 diet, the inotropic response to added Ca2+ was only 60% of that in euthyroid controls and 50 and 65% of euthyroid controls in n-6 and SAT diet-fed animals, respectively. Although the response was again lower in n-3-fed animals, the differences among the diet treatments were not as great as those seen in euthyroid animals, and there were no apparent diet-dependent differences in sensitivity to Ca2+ in hypothyroid animals. The potency of the calcium-channel blocker nifedipine was diet-dependent in euthyroid animals, with the order of decreasing sensitivity being n-3 > n-6 > SAT. Papillary muscles were not as sensitive to nifedipine in hypothyroid animals, although n-3-fed animals again showed the greatest inhibition of tension development. On the other hand, nitrendipine-binding affinity was not different among euthyroid and hypothyroid animals fed the n-6 diet.(ABSTRACT TRUNCATED AT 250 WORDS)
