Impaired vascular reactivity is a hallmark of several cardiovascular diseases that include hypertension and diabetes. This study compared the changes in vascular reactivity in age-matched experimental hypertension and diabetes, and, subsequently, tested whether these changes could be affected directly by ascorbic acid (10 microM). Endothelium-derived nitric oxide (NO) modulation of ascorbic acid effects was also investigated. All the experiments were performed in the presence of a cyclooxygenase inhibitor, indomethacin (10 microM). Results showed that the endothelium-dependent and -independent relaxations induced by acetylcholine (ACh) and sodium nitroprusside (SNP), respectively, were blunted to a similar extent in isolated aortic rings from age-matched spontaneously hypertensive (SHR) (R(max): ACh = 72.83+\/-1.86%, SNP = 96.6+\/-1.90%) and diabetic (Rmax: ACh = 64.09+\/-5.14%, SNP = 95.84+\/-1.41%) rats compared with aortic rings of normal rats (Rmax: ACh = 89%, SNP = 104.0+\/-1.0%). The alpha1-receptor-mediated contractions induced by phenylephrine (PE) were augmented in diabetic (Cmax = 148.8+\/-9.0%) rat aortic rings compared to both normal (Cmax = 127+\/-6.9%) and SHR (Cmax = 118+\/-4.5%) aortic rings. Ascorbic acid pretreatment was without any significant effects on the vascular responses to ACh, SNP and PE in aortic rings from normal rats. Ascorbic acid significantly improved ACh-induced relaxations in SHR (Rmax = 89.09+\/-2.82%) aortic rings to a level similar to that observed in normal aortic rings, but this enhancement in ACh-induced relaxations was only partial in diabetic aortic rings. Ascorbic acid lacked any effects on SNP-induced relaxations in both SHR and diabetic aortic rings. Ascorbic acid markedly attenuated contractions induced by PE in aortic rings from both SHR (Cmax = 92.9+\/-6.68%) and diabetic (Cmax = 116.9+\/-9.4%) rats. Additionally, following inhibition of nitric oxide synthesis with l-NAME, ascorbic acid attenuated PE-induced contractions in all aortic ring types studied. These results suggest that (1) vascular hyper-responsiveness to alpha(1)-receptor agonists in diabetic arteries is independent of endothelial nitric oxide dysfunction; (2) ascorbic acid directly modulates contractile responses of hypertensive and diabetic rat aortas, likely through mechanisms in part independent of preservation of endothelium-derived nitric oxide.<\/p>\n
Machha Ajay,\u00a0Mohd Rais Mustafa<\/p>\n
<\/p>\n
Summary Impaired vascular reactivity is a hallmark of several cardiovascular diseases that include hypertension and diabetes. This study compared the changes in vascular reactivity in age-matched experimental hypertension and diabetes, and, subsequently, tested whether these changes could be affected directly by ascorbic acid (10 microM). Endothelium-derived nitric oxide (NO) modulation of ascorbic acid effects was…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[69],"tags":[545],"_links":{"self":[{"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/posts\/7248"}],"collection":[{"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/comments?post=7248"}],"version-history":[{"count":0,"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/posts\/7248\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/media?parent=7248"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/categories?post=7248"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.healthlibrary.info\/wp-json\/wp\/v2\/tags?post=7248"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}