Neiguan Anti-rat Acute Myocardial Ischemia In The Autonomic Nervous Mechanism. Ea Study

Objective: Anti-AMI (acute myocardium ischemia) effect of electric needle stimulating PC6 was to be studied according to ECG, heart sympathetic and vagi nerve discharging, cardiac muscie ultrastructure of AMI rats being needled guided by the meridian (acupoints)-viscera relation theory, especially PC6-heart relation. Potential active substance and action passage was to be found out for PC6-heart relation on autonomic nerve anti-AMI effect to understand the regulating mechanism of nervous endocrinological system so as to provide reliable experimental evidence for PC6-heart relation theory with SP of autonomic nerve and NOS as observing index.Methods: 48 SD rats were randomly divided into normal group×2 (A and A'), controlled group×2(B and B'), electric needle groups (C and C'), blocker group (D), electric needle with blocker group (E) with 6 rats in each group. AMI models were induced by Pit iv, treated by the left PC 6 stimulated with electric needle. Each group was as follows"For normal group (group A): cervical vagi and sympathetic nerves were isolated, BL-420E⁺ was applied to record ECG, vagi and sympathetic nerve discharging, models were made 3 min later, and myocardium pieces were taken for electron microscope section 0 min, 3 min, 8 min, 13 min, 23 min, 33 min, 43 min, 53 min after the recording times being marked.ECG was not recorded for rats in group A', and spinal cord and brain were taken as section for the immunohistochemistry determination of SP and NOS in 23 min.Controlled group (group B)" ECG, vagi and sympathetic nerve discharging were recorded with BL-420E⁺ after cervical vagi and sympathetic nerves were isolated, models were made 3 min later, and record times were marked correspond to that in group A 0 min, 5 min, 10 min, 20 min, 30 rain and 40 min before and after the model establishment respectively. The myocardium pieces were taken as electron microscope sections. ECG was not recorded for rats in group B', and spinal cord and brain were taken as section for the immunohistochemistry determination of SP and NOS in 20 min.Electric needle group (group C): ECG, vagi and sympathetic nerve discharging were recorded with BL-420E⁺ after cervical vagi and sympathetic nerves were isolated, models were made 3 min later, and were marked 0 min, 5 min, 10 min, 20 min, 30 min and 40 min later. PC6 on the left arm (between the ulna and radius 3mm from waist joint, refer to "Rats Acupoints Figure" of Hua Xing Bang,) was stimulated with electric needle high and low frequency (from 8 to 80Hz, alternatively for 14 times/min, voltage: 1.5 v, current: 1 mA) for 5 min. The needle without electric stimulator remained for 15 min. The myocardium pieces were taken as electron microscope sections. ECG was not recorded for rats in group C', and spinal cord and brain were taken as section for the immunohistochemistry determination of SP and NOS 20 min after the model was established.Blocker group (group D): NK₁ receptor blocker (250 nmol/kg)was given in the left femoral vein min before vagi and sympathetic nerve discharging were recorded. For other operations, refer to group B'.Electric needle with blocker group (E): NK₁ receptor blocker (250 nmol/kg) was given in the left femoral vein 30 min before vagi and sympathetic nerve discharging were recorded. For other operations, refer to group C'.Observation index:(1) Heart rate from ECG of different times, ST (mv) (10 samples were taken 1 min after each time, for the mean)(2) Frequency (Hz) of vagi and sympathetic nerve discharging of different times (10 samples were taken 1 min after each time, the sample time lasts for 1s, for the mean of sum)(3) The ultrastructure was observed.(4) Paraventricular nucleus (PVN) of hypothalamus, medullary bulb and vagi nerve complex, spinal lateral crus OD of SP and NOS (HPIAS-1000 was applied to scan the brown yellow and blue random mating signal. Three corresponding visual fields of four slices from PVN of hypothalamus, medullary bulb and vagi nerve complex, C₈-T₂ were taken. Then the averages of the sum of 12 visual fields for each index were the SP or NOS immunopositive OD) were observed.Data processing: (?)±s stands for experimental data of each group. SPSS 12.0 software was applied for the data within and between groups, with the P=0.05 as the significance high limit.Results: 1. ECG: there was no significance for the heart rate of different times, ST within group A. While the heart rate and ST differed significantly in group B from 0 min to 40 min after AMI model being made than before (P＜0.05), however, no significant data showed that there was the difference 50 min later. There was significant difference any time from 0 min to 20 min and 20 min, 30 min and 40 min after the model (P＜0.05) in group C comparing with group B (P＜0.05).2. Ultrastructure of myocardium: the arrangement of myofibrii was in order, with muscle segments being of the same length, myofilament being clear, mitochondrion being normal without swelling, electrodensity of hemangioendothelial cell being even, pinosome being rich in group A.The myocardial cells were swelling obviously, and the arrangement of myofibril was in disorder, with muscle segments being of the different length, much fibers fracture being seen and deformation being in intercalated disk, mitochondrion being swelling as typical sac, the nucleus shrinking, hemangioendothelial being swelling severely, pinosome being reduced, and uneven electrodensity, some of the endothelial separating from the body in group B.The myocardial cells were swelling slightly, the myofibril was loosen, with some of myofilament being unclear, mitochondrion being swelling slightly, its membraneeing unclear some of them as typical sacs, some of the nucleus shrinking, hemangioendothelial being swelling, pinosome being reduced in group C.3. Autonomic nerve discharging: the sympathetic and vagi nerve discharging frequency differed not so obviously before and after in group A. The vagi nerve discharged more each time from 0 min to 40 min after and sympathetic nerve discharging less after significantly (P＜0.05) with group B. It was significant comparing with group A (P＜0.05). Vagi nerve discharged less and sympathetic nerve discharged more in group C after being stimulated by the electric needle (that is 10 min to 40 min after the model being made). There was no significance comparing with that in group A, and showed significance comparing with that in group B.The result of group A', group B', group C' showed to be similar with that of group A, group B and group C. For detail see experiment 2. The vagi nerve discharging increased and sympathetic nerve discharging reduced in group D and E 0 min and 20 min after and were significant comparing with group A (P＜0.05). However, the nerve discharging between group D and E before and after were not significant different. The nerve discharging 10 and 20 min after were significantly different between group E and C (P＜0.05).4. OD of SP: the OD of SP in PVN of hypothalamus, medullary bulb and vagi nerve complex, spinal lateral crus were 115.4±12.2, 84.6±14.5, 43.3±12.1 in group A. OD of SP was lower in group B' than that in group A and the difference was significant between groups (P＜0.05). SP were more in any parts in group C' than in group A' and group B' and the difference was significant between groups (P＜0.05). The positive expression of SP in three parts in group E were lower than that in group C' significantly (P＜0.05). There was no significant difference of SP between group E and D.5. OD of NOS: the OD of NOS in PVN of hypothalamus, medullary bulb and vagi nerve complex, spinal lateral crus were 98.0±14.7, 64.6±12.3, 40.3±10.4. in group A. OD of NOS of any parts were higher in group B' than those in group A and the difference was significant between groups (P＜0.05). The positive expression of NOS in three parts in group D and E increased significantly comparing with that in group A' (P＜0.05). The difference was significant between group E and C' (P＜0.05). There was no significant difference between group E and D.Conclusion: 1. Electric needles stimulating PC6 promotes heart rate and recovery of ST, protects myocardial cells, myofibril, mitochondrion and nucleus of AMI rats, which serves as another evidence for protect effect of that therapy on AMI.2. Electric needles stimulating PC6 inhibits AMI vagi nerve and excites sympathetic nerve and therefore promote the recovery of AMI.3. Electric needles stimulating PC6 promotes the SP positive expression and reduces NOS activity in PVN of hypothalamus, medullary bulb and vagi nerve complex, C8-T2 spinal lateral crus. The SP in spinal lateral crus increases and further promotes the sympathetic nerve discharging and inhibits vagi nerve. Sympathetic nerve is to contract the heart muscles and promote myocardial circulation, while the vagi nerve inhibited decreases the myocardial impairment. The lower activity of NOS might reduce the side effect of free radical NO to the heart muscles.4. NK1 iv receptor blocker blocks the adjustment of electric needles stimulating PC6 to autonomic nerve and further leads to the descent of SP positive expression, ascent of NOS activity. The blocker serves as another evidence for the SP as an important substance for AMI in a different aspect.5. SP and autonomic nerve and central adjustment serve as the theoretical base for PC6-heart relation.6. The new ideas: Autonomic nerve adjusting effect on AMI was studied, and PC6-heart relation was discussed from the view of SP of autonomic nerve and NOS expression. Few reports have been published on the antagonistic effect on SP was firstly observed with receptor blocker NK1â…³.