2,3 Dioxoindoline Regulation Of Cardiovascular Function In Diabetic Rats

Objective Diabetes is a common endocrine diseases, may be complicated by hypertension, arrhythmia, myocardial hypertrophy and interstitial fibrosis, heart failure and other cardiovascular diseases, has become a major cause of death and disability for diabetes, and how early diagnosis, prevention and effective control and continuation of the process of cardiovascular complications of diabetes has become a important question. Endogenous active substancesfor the readjustment of the cardiovascular system have increasingly caused wide attention.2,3-isatin (isatin, ISA) is an inhibitor of atrial natriuretic peptide (ANP) receptor (NPR-A), is an endogenous compound with anti-atherosclerosis, antioxidant properties. ANP is an important vascular active substance, which can exert sodium and volume homeostasis, visodilatilation, antioxidant activity, inhibition of cell proliferation, myocardial fibrosis effects on the cardiovascular system. However, the current the effect of ISA on the regulation of cardiovascular function and the mechanism is not clear. Therefore, this study established a stable diabetic rat model, to define the effect of ISA on cardiovascular function and the mechanisms involved.Methods1. Healthy male Wistar rats were randomly divided into control (Sham group), diabetes (DM group) and difference dose of ISA lavage DM group (ISA). Sham group:normal diet feed90days; DM groups:high-fat diet feed45days, intraperitoneal injection of50mg/kg streptozotocin (STZ), continue to high-fat diet feed45days; ISA group:high-fat diet feed45days, intraperitoneal injection of50mg/kg STZ, continue to high-fat diet feed after30days, lavage50mg/ml,100mg/ml and200mg/ml ISA respectively (once a day,15days), continue to high-fat diet feed. Parameters including cardiac mass index, systolic and diastolic blood pressure, heart rate and the levels of plasma atrial natriuretic peptide (ANP) were observed. At the same time observe the shape variation of cardiac and thoracic aorta.2. Experiments were performed in isolated thoracic aortic rings. Vascular tension changes of ISA were examined in thepresence or absence of phenylephrine (PE). L-NAME, a non-selective NOS inhibitor, and ODQ, a selective inhibitor of soluble guanylyl cyclase (sGC), were used to block the effect of isatin. Also, the effect of acetylcholine (ACh)-induced vasorelaxation was observed in thepresence of isatin.3. The atria were perfused for60min to stabilize ANP secretion.[3H] Inulin was introduced to the pericardial fluid20min before the start of the sample collection. The perfusate was collected at2min intervals at4℃for analyses. Control cycles (12min) were followed by an infusion of ISA or ACh in order to observe the effect of ISA or ACh alone. The control period (12min) was followed by an infusion of ACh for36min, then ACh was followed by an infusion of ISA for36min. The changes in atrial stroke volume and atrial pulse pressure were measured via a pressure transducer. The immunoreactive ANP in perfusate were measured by radioimmunoassay (RIA). Results1. Blood glucose of control group were6.38±0.31mM, DM group were17.15±0.98mM. And for ISA intervention group, the blood glucose were15.38±1.04mM, both DM and ISA rats have significantly difference from the control group (p<0.01). The body weight of control group were446.25±3.90g, DM rats were351.00±41.02g, significantly difference from the control group (p<0.01). While the ISA intervention group rats were409.40±19.71g, there was a significant differences compared with the DM group(p<0.01), no significant difference compared with control group (p>0.05). Plasma ANP concentrations of control group were0.1241±0.0254ng/ml, DM group was0.3281±0.0516ng/ml(p<0.01vs. control group), and plasma concentrations of ANP of ISA intervention group were0.0605±0.0283ng/ml, no significantly difference compared with control group(p>0.05). Blood pressure tended to increase in DM group compared with control group. For ISA intervention group, both systolic and diastolic blood pressure decreased compared with the control group (p<0.05). Diabetic rat heart rate decrease compared with control rats, a difference compared with the control group. ISA rat heart intervention group difference(p<0.05) compared with the control group. Diabetic rats with focal areas of myocardial inflammatory cell infiltration, myocardial cells dissolve change. Diabetic thoracic aorta adventitia thickening, intimal damage, smooth muscle cells become larger, irregular arrangement.2. ISA(1-1000μM)contracted PE-pretreated aortic rings in a concentration-dependent manner, but not in the absence of PE. Endothelium-denudation abolished the ISA-induced contraction in PE-pretreated aortic rings. L-NAME(10μM)and ODQ(10μM)blocked the ISA-induced contraction in PE-pretreated aortic rings. ACh-induced vasorelaxation was attenuated by the pretreatment of ISA.3. ISA induced decreases in atrial myocytic ANP release and pulse pressur in a concentration-dependent manner, and this effect was reinforded in the atrium from diabetic rats. The effect of ACh accentuated the ISA-induced decrease in atrial ANP release was attenuated in the atrium from diabetic rats.Conclusion ISA intervention treatment can improve cardiovascular function in diabetic rats.ISA could induce the contraction of thoracic aorta through the inhibition ofendothelium dependent NO-cGMP signaling pathway and the attenuation of ACh-induced relaxation. The present data alsosuggestthat ISA-induceddecreasein atrial ANP releasewas reinforced in the atrium from diabetic rats. The effect of ACh accentuated the ISA-induced decrease in atrial ANP release was attenuated in the atrium from diabetic rats. These findings indicate that effect of ISA on cardiac function and thoracic aortic relaxation were alterted in diabetic rats.