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Environmental Determinants of Cardiovascular Disease

Environmental Determinants of Cardiovascular Disease

Aruni Bhatnagar

The effect of sunlight on cardiovascular health. The visible range of sunlight regulates the master clock located in the pacemaker neurons of the suprachiasmatic nucleus, which sets the intrinsic 24-h cycle and synchronizes the light-insensitive peripheral clocks to coordinate cycles of waking, sleeping, and feeding. The UVB radiation converts 7-dehydrocholesterol in the epidermis to pre–vitamin D3, which undergoes thermal isomerization to vitamin D. Vitamin D3 formed in the skin appear in the circulation and is then transported to the liver where it is converted to 25(OH)D3. In kidney, 25(OH) D3 undergoes hydroxylation to form biologically active 1,25(OH)2D. The UVA radiation induces photodegradation of nitrosothiols, such as S-nitrosylglutathione, which leads to the generation of NO, an important regulator of blood pressure. (Illustration credit: Ben Smith.) [Powerpoint File]