Effects And Mechanism Of Canagliflozin On Vascular Function And Blood Pressure Regulation

Background: Several large-scale clinical studies have suggested that canagliflozin(a new generation of oral hypoglycemic agents)can improve the prognosis of cardiovascular events in patients with type 2diabetes.The proportion of hypertension in diabetic patients is much higher than that in non-diabetic patients.Both diabetes and hypertension share similar pathogenic factors(obesity,genes,etc.),and similar mechanism of cardiovascular injuries(vascular endothelial injury and upregulated levels of inflammation,etc.).Large clinical trials have suggested that canagliflozin can reduce blood pressure in patients with type 2 diabetes,but the underlying mechanism has not been fully explained.Objective: The purpose of this study was to explore whether canagliflozin was involved in blood pressure regulation by improving vascular function.Methods:(1)We detected the effects of vasoactive substances on isolated vascular segments derived from spontaneous hypertensive rats(SHR)and WKY rats with the help of myograph to evaluate the effect of hypertension on vascular function.We intervened the isolated blood vessels with canagliflozin to test whether the inhibitors had potential vascular activity.The effects of canagliflozin on vascular endothelial function was observed in isolated vascular tissues cultured with high level of glucose.(2)Blood pressure,blood glucose and body weight of C57-leprdb/leprdb(db/db)and db/m mice were measured.Ang-II subcutaneous micropumping method was conducted to construct hypertension models,and the effects of canagliflozin on vascular function were detected after intervention.The expression levels of endothelial nitric oxide synthase(e NOS),serine/threonine kinases(Akt),phosphorylated endothelial nitric oxide synthase(p-e NOS)and phosphorylated serine/threonine kinase(pAkt)in vascular tissues were measured by western blot.The level of advanced glycation end products(AGEs)in vascular tissue was measured by ELISA kit.(3)The effects of AGEs on e NOS and Akt pathways of HUVECs were detected at m RNA and protein levels.The proliferation and migration of r SMCs(derived from SHR rats)were observed after intervention with canagliflozin.The effects of AGEs on the proliferation and phenotype of r SMCs were observed,and the role of canagliflozin in this process was detected.Results:(1)The blood pressure of SHR rats was significantly higher than that of WKY rats(SBP: +59.88±3.730 mm Hg,P<0.01;DBP: +77.33±3.576 mm Hg,p<0.01).Vasodilation function of SHR rats was significantly impaired compared with WKY rats.High-glucose culture could significantly down-regulate isolated vascular endothelium-dependent vasodilation(p<0.01).Canagliflozin showed vascular activity,possibly through Type 1 sodium-hydrogen exchangers(NHE-1).Moreover,endothelium-dependent vasodilation was significantly improved in the canagliflozin treatment group under high-glucose culture(p<0.05).(2)Ang-II intervention increased blood pressure in db/db)and db/m mice(db /db group: SBP,+29.45±2.231 mm Hg/DBP,+22.30±1.833 mm Hg;db/m group: SBP,+23.20±2.095 mm Hg/DBP,+18.60± 2.042 mm Hg)),while The mean blood pressure of db/db+Ang-II+CANA group was lower than that of db/db+Ang-II group(SBP,-17.20 ± 2.494 mm Hg,p<0.01;DBP,-12.10 ± 1.790 mm Hg,p<0.01).Canagliflozin improved vasodilation function(p<0.01)and reversed the low activation state of e NOS in the aortic tissues induced by Ang-II,raised the ratio of pe NOS/e NOS(db/db group: +0.139 ± 0.018,p=0.0015;db/m group:+0.043 ± 0.011,p=0.0017).Canagliflozin intervention could reduce the deposition of AGEs in aortic tissues(db/db group:-36.53 ± 4.509ug/m L,p=0.0013;db/m group:-10.17 ± 3.300 ug/m L,p=0.0368).(3)MGO(methylglyoxal)intervention can inhibit the phosphorylation of e NOS and Akt in endothelial cells,and promote the proliferation(p=0.0189),migration(p=0.0003),and phenotypic transformation of r SMCs(p=0.0016).Canagliflozin can directly inhibit the proliferation and migration of r SMCs and reverse the effects of AGEs on proliferation(p=0.0001),migration(p=0.0055),and phenotype of r SMCs(p=0.0043).Conclusion:(1)Canagliflozin had the properties of vasoactive substance that can directly induce non-endothelium-dependent vasodilation.(2)Canagliflozin participated in blood pressure regulation by improving endothelium-dependent and non-endothelium-dependent vasodilation in animal models and reducing arterial response to vasoconstrictor.(3)Canagliflozin improved endothelium-dependent vasodilation by reducing the deposition of advanced glycation products in the arterial tissues,thereby increasing the activation of Akt and e NOS in endothelial cells.(4)Canagliflozin improved the effects of advanced glycation end products on proliferation,migration and phenotypic transformation of smooth muscle cells by acting on type 1 sodium-hydrogen exchangers.27 figures,13 charts,150 references.