Study Of ECG And BP Signals In Renal Artery Stenosis And LNAME-induced Hypertensive Rats

BackgroundHypertension has become an important factor endangering human health because of its increasing morbidity and mortality.Essential hypertension and renal vascular hypertension are the most common diseases in hypertension.Both types of hypertension can cause damage to autonomic nervous system,which is manifested by heart rate variability and blood pressure variability.It has become an important research direction to study hypertension by analyzing heart rate variability and blood pressure variability.However,there is no clear report on the difference between heart rate variability and blood pressure variability and the damage of autonomic nervous system caused by these two diseases.Objective1.To clarify the changes of heart rate variability(HRV)and blood pressure variability(BPV)in essential hypertension(EH)rats induced by L-nitrosoarginine methyl ester(LNAME)and renovascular hypertension(RH)rats induced by 2 kidneys 1 clip(2K1C)during the development of hypertension,and the differences in the pathogenesis of hypertension.2.To explore the changes of HRV and BPV in a short time after forced feeding of LNAME.Method1.Healthy SD rats were forcibly fed with LNAME(40mg/kg/day)to prepare the model of essential hypertension rats,and the model of renovascular hypertension rats was made by stenosis of unilateral renal artery(2K1C)to 0.25 mm;2.The ECG and BP signals of LNAME-induced hypertensive rats were continuously collected by implantable physiological signal acquisition system within 100 minutes after administration for five weeks,and ECG and BP signals of unilateral renal artery stenosis rats within four weeks after renal artery stenosis were collected;3.After pretreatment of ECG and BP signals of experimental rats,RR interval sequences were detected from continuous ECG signals,systolic and diastolic blood pressure sequences were detected from continuous blood pressure signals,and these sequences were analyzed by time-frequency and time-domain methods to extract the characteristic values of heart rate variability and blood pressure variability sequences;4.The characteristic values of heart rate variability,systolic blood pressure variability and diastolic blood pressure variability of experimental rats were analyzed,and the differences of heart rate variability and blood pressure variability between the two groups were studied.Result1.The energy entropy of RR interval sequence in EH and RH groups was significantly lower than that in control group(RH,EH<Control group:0.31±0.03,0.34±0.023<0.61±0.0179).The change process was tested by Kolmogorov-Smirnov(KS),and there were significant statistical differences between LNAME and 2K1C groups and control group(P<0.01).2.The energy entropy of systolic blood pressure sequence in RH group<EH group<control group(2.06±0.17<2.4±0.11<2.83 ± 0.098)after the third week of signal acquisition,and the changes of RH and EH in control group were significantly different by KS test(P<0.01),There was significant difference between RH group and EH group after KS test(P<0.01);The time-frequency entropy of systolic blood pressure sequence in RH group<EH group<control group after the third week of signal acquisition.The changes of RH and EH group were significantly different between control group(P<0.01).The changes of RH and EH group were significantly different after KS test(P<0.01).The changes of RH and EH group were significantly different after KS test(P<0.01).3.After forcibly feeding LNAME,the time-frequency entropy of RR interval decreased by 0.3 at 80 min,and the change process showed significant statistical difference by KS test(P<0.01),which returned to the level of paired groups at 100 min.The time-frequency entropy of the sequence of systolic and diastolic blood pressure variability decreased by 0.2,which was significantly different by KS test(P<0.01),and maintained at 100 min.Conclusion1.Compared with essential hypertension rats induced by LNAME,renovascular hypertension rats with slower autonomic nervous damage,but the degree of vascular function damage is stronger than that of essential hypertension rats.2.Rats forcibly fed LNAME within short time had stronger damage of vasoconstriction-diastolic function in rats.