Mechanisms Of Myocardial Metabolites On Myocardial Contractility In Healthy And Hypertensive Rats

Purpose:To explore the effects of different concentrations of palmitic acid(PA)on the contractility of left ventricular myocytes in healthy and hypertensive rats.In addition,for influence on hypertensive myocardial contractility if high glucose was given simultaneously.Finally,the impact way from PA on the contractility was also our studied purpose.Methods:Angiotensin ? was injected into rats by implanting micro-osmotic pump subcutaneously to prepare a hypertensive rat model.In order to prepare a sham-operated control group,rats were operated on the same way but not implanted with Angiotensin ? micro-osmotic pump;Left ventricular myocardial cells were isolated using Langendorff perfusion system enzymatic method;The IonOptix system was used to measure the changes in the length of myocytes sarcomere in the left ventricular myocardium induced by electrical stimulation and observe the degree of contraction;Fura 2 fluorescence assay detection method was used to measure the transient intracellular calcium concentration and myofibril calcium sensitivity;ATPLite chemiluminescence kit was used to measure the intracellular ATP level.Results:1.PA increased the contractility of left ventricular myocytes in normal rats(P<0.001,n=18),but PA did not increase the contractility of left ventricular myocytes in hypertensive rats(P=02,n=18).2.Under the condition of high glucose,the contractility of left ventricular myocytes in normal rats was not affected by PA(P=0.8,n=30),but the contractility of left ventricular myocytes in hypertensive rats was significantly increased(P<0.001,n=19).3.It had no effect on the concentration of calcium and the sensitivity of myofilament of left ventricular myocytes in normal and hypertensive rat(Fura 2 at wavelength F360/F380:P=0.64,n=34 and n=24,between PA and control in shams;P=0.66,n=36 and n=27 between PA and control in hypertension;between shams and hypertension in control group,P<0.001;between shams and hypertension in PA,P<0.001).4.PA could increase the intracellular ATP level of rats in the sham operation group,but did not increase the ATP level of hypertensive rats(In the sham operation group,the control group and the PA group,P=0.01,n=21;the control group and the PA group in the hypertensive rats,P=0.53,n=21).Conclusions:1.Palmitic acid can increase the contractility of healthy cardiac myocytes,but it have no obvious positive effect on the cardiac myocytes in hypertensive rats.2.In a high glucose state,the contractile force of normal myocardium do not change significantly,but the myocardial contractility of hypertensive rats increased.3.Palmitic acid enhances myocardial contractility by increasing ATP levels in the myocardium.