Inhibitory effect of activation of cardiac TRPV1 receptors on cardiovascular activity in rats / 吉林大学学报(医学版)

Objective: To investigate the cardiovascular reflex induced by the activation of cardiac transient receptor potential vanillic acid receptor 1(TRPV1), the central location of reflex and its peripheral neurotransmitters of the rats, and to elucidate the central and peripheral neural mechanisms of cardiovascular reflex mediated by TRPV1 receptor. Methods: A total of 60 healthy male SD rats were randomly divided into control group, ido-RTX group, atropine group, immunofluorescence group and nerve tract tracking group; there were 12 rats in each group. Pericardial intubation was performed in the rats in various groups after anesthesia. The changes of heart rates and blood pressures of the rats in control group, ido-RTX group and atropine group were observed by arterial intubation. The tissue samples were collected 1 h after intropericardial injection of capsaicin in imunofluorescence group, and the co-expression of c-Fos positive neurons induced by capsaicin and cholinesterase positive neurons in the medulla oblongata was observed by immunofluorescence technigue. Intraopericardial injected carbonyl cyanine fluorescent dye (Dil) was used as retrograde tracer in nerve tract group, and the distribution of Dil positive cells in the medulla oblongata was observed by fluorescence microscope 1 week later. Results: The blood pressure and heart rate of the rats in control group were decreased significantly after intrapericardial injection of capsaicin of the rats in control group (P0. 05); after intrapericardial injection of capsaicin, the number of c-Fos positive neurons in nucleus tractus solitarii, dorsal motor nucleus of vagus and nucleus ambiguous of medulla oblongata was increased significantly (P<0. 05); most of these neurons were cholinesterase positive neurons; after intrapericardial injection of Dil, a large number of red fluorescent labeled neurons and nerve endings appeared in the nucleus tractus solitarii, dorsal motor nucleus of vagus and nucleus ambiguous. Conclusion: Intrapericardial injection of capsaicin can selectively activate the TRPV1 receptors in the heart, increase the excitability of cholinergic neurons in the cardiovascular center of the medulla oblongata, increase the peripheral release of acetylcholine, and produce an inhibitory effect on the cardiovascular activity by activating the M receptor.

Valsalva ratio: a measure of stress in first year medical students.

Background: The Valsalva manoeuvre is commonly used as a method of assessing normal or disordered Autonomic control of Blood pressure and Heart Rate. Continuous changes in sympathetic and parasympathetic neural inputs exhibits alteration in Heart Rate and blood pressure which causes oscillation of R-R interval. Acute and short term stress leads to rapid changes throughout the body. Almost all body system gear up to meet the perceived dangers (stress).When healthy subjects are acutely stressed Heart rate increases and R-R interval on ECG decreases transiently. The purpose of the study is to see the changes in VMM in prestress and stress conditions. Methods: 56 non-smoking apparently healthy first year medical students (26 males and 26 females) were selected for the present study. Data collected two month prior to the examination as prestress values and during examination as during stress values. Data analyzed using Wilxcon Rank signed 2 tailed test and the sub groups data analyzed paired t test. Results: 11.54% males and 19.23% females had mild stress in prestress condition. During stress 46.15% males and 19.23% females had mild stress while 34.62% males and 57% of females had severe stress. The female had more stress as compared to males both in prestress and during stress conditions. Conclusion: We conclude that VR is affected by the academic stress in the first year medical students and that among them females are more affected which may be due to the new environment and new protocol of the education system.

Autonomic Neuropathy in Healthy Elderly Person.

Background: Cardiac autonomic nerve function can be affected in older age. Objective: To find out the degree of autonomic neuropathy by autonomic nerve function scoring system in apparently healthy elderly subjects. Methods: This cross sectional study was conducted in the Department of Physiology, BSMMU, Dhaka between July 2005 and June 2006.For study group, 30 elderly subjects age ranged from 51-60 years were enrolled in one group whereas another 30 elderly subjects age between 61-70 years were enrolled in another group. For comparison sex and BMI matched thirty apparently healthy adults with age from 21-30 years were studied as control. Autonomic nerve function status of all the subjects were examined by five simple non-invasive cardiovascular reflex tests Valsalva maneuver deep breathing test, orthostatic test handgrip test, and sudden standing. Autonomic nerve function (ANF) scoring was done to find out the degree of autonomic neuropathy. Results: 23.34% of subjects of 61-70 years group showed autonomic nerve dysfunctions and 20% had early involvement and 3.34% of them had definite involvement of Autonomic neuropathy. But this percentage was relatively less (10%) in 51-60 years who had early involvement and none had found definite involvement whereas autonomic nerve function was normal in 21-30 years age group.. Conclusion: From this study, it can be concluded that aging process substantially impaired cardiovascular autonomic nerve function.

Parasympathetic Nerve Function Status in Female with Rheumatoid Arthritis.

Background: Sudden cardiac death in patients with Rheumatoid Arthritis has been attributed to the decreased vagal drive to the heart. Objective: To assess cardiac parasympathetic nerve function status in patients with Rheumatoid Arthritis (RA). Methods: This cross sectional study was conducted in the Department of Physiology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Shahbag, Dhaka from January to December 2010. Sixty female RA patients aged 18-50 years were included in the study group. They were enrolled from the Out Patient Department of Rheumatology Wing of the Department of Medicine, BSMMU, Dhaka. For comparison age matched thirty apparently healthy females were also studied as control. To assess parasympathetic nerve function status, all the subjects were examined by three noninvasive cardiovascular reflex tests such as heart rate response to valsalva maneuver (valsalva ratio), heart rate response to deep breathing and heart rate response to standing (30th :15th ratio). For statistical analysis independent sample t test was used. Results: Mean values of valsalva ratio, deep breathing test and 30th :15th ratio were significantly (p<0.001) lower in rheumatoid arthritis patients compared to those of healthy control. Conclusion: From this study it may be concluded that lower cardiac parasympathetic nerve activity characterized the autonomic nerve dysfunction in patients with Rheumatoid Arthritis.

Damage of autonomic nerve function in diabetic patients with gastrointestinal symptoms / 中华全科医师杂志

Objective To observe autonomic nerve function damage in diabetic patients with gastrointestinal symptoms. Methods Twenty-four patients of diabetes mellitus (DM) with gastrointestinal symptoms, as well as 20 cases of DM without gastrointestinal symptoms and 17 health volunteers were recruited from the clinic of gastroenterology, Jishuitan Hospital, Beijing during December 2008 to May 2009, and standard cardiovascular reflex test was performed for all of them to determine their functions of the autonomic nerve. Results Respiratory rate (an indicator of parasympathetic nerve function) was ( 14 ± 5 ) times per minute in patients of DM without dyspepsia, obviously lower than that in healthy controls [(20±10) times per minute], and that in patients of DM with dyspepsia was (9 ±6) times per minute, obviously lower than that in healthy controls and asymptomatic ones ( P ＜ 0. 05 ). Scores of five indicators of the autonomic nerve functions, and the sympathetic, parasympathetic nerve and overall autonomic nerve functions were significantly higher in patients of DM with gastrointestinal symptoms than those in the patients without dyspepsia and healthy controls. Abnormality rate of autonomic nerve functions was 96 percent (23/24) in the patients with dyspepsia, 58 percent (14/24) in those definitely and seriously involved, and five percent (1/20) in those without dyspepsia. Conclusions Autonomic neuropathy exists in most diabetic patients with dyspepsia, both sympathetic and parasympathetic nerve involved. Impairment of parasympathetic nerve function occurs earlier than that of sympathetic nerve in patients of DM.

Parasympathetic Nerve Function Status in Postmenopausal Women.

Background: In postmenopausal women, the risk of cardiovascular diseases gradually increases and alterations in autonomic nerve functions commonly affect cardiac vagal control. Objective: To observe some aspects of parasympathetic nerve function status in apparently healthy post menopausal women. Method: This cross sectional study was carried out in the Department of Physiology Bangabandhu Sheikh Mujib Medical University. In this study, 30 postmenopausal women with age 45 to 60 years were included in group B (study group) and 30 premenopausal women aged 20 to 30 years were taken in group A (control group). They were further divided into group A1(menstrual),A2(follicular), A3(luteal) according to phases of menstrual cycle during which they were studied. Serum estrogen and progesterone levels were measured in postmenopausal women and also during follicular and luteal phases in premenopausal women and were estimated by MEIA technique. To assess parasympathetic nerve function status, three noninvasive cardiovascular reflex tests such as heart rate response to valsalva maneuver, heart rate response to deep breathing and heart rate response to standing were performed in all the subjects. Data were collected by recording ECG in resting conditions. For statistical analysis, unpaired t test and multiple regression analysis was used. Results: In postmenopausal women, serum estrogen and progesterone levels were significantly (p<0.001) lower compared to those of follicular and luteal phases of premenopausal women except progesterone level during follicular phase which was though lower but not statistically significant. Heart rate response to valsalva maneuver were almost similar in all the groups.Heart rate response to deep breathing and heart rate response to standing were significantly lower in group B than those of group A1, A2 and A3 respectively. On regression analysis parasympathetic nerve function in post postmenopausal women showed significant association with estrogen level. Conclusion: From this study it may be concluded that parasympathetic nerve function was lower in postmenopausal women, which may be related to decreased level of estrogen.

Evaluation of Parasympathetic Nerve Function Status in Healthy Elderly Subjects.

Background: Autonomic control on cardiovascular activity is modified with age. Impaired autonomic nerve functions are common features of patients suffering from cardiovascular diseases particularly in old age. Objective: To observe the influence of aging process on parasympathetic nerve function. Study design: This observational study was conducted in the Department of Physiology, BSMMU, Dhaka during the period of July 2005 to June 2006. For this purpose, 60 apparently healthy elderly subjects of both sexes were selected as study group and divided into two groups-one group consisted of 30 elderly subjects with age ranged from 51-60 years and another group consisted of 30 elderly subjects with age ranged from 61-70 years. Thirty sex and BMI matched healthy adults with age ranged from 21-30 years were studied as control. Methods: Parasympathetic nerve function status of all the subjects were assessed by three simple non-invasive cardiovascular reflex tests. These were heart rate response to valsalva maneuver, heart rate response to deep breathing and heart rate response to standing (30th:15th ). For statistical analysis one way ANOVA (Post Hoc Test) and the Pearson’s correlation co-efficient tests were done. Results: Mean (± SD) of valsalva ratio were 1.50±0.23, 1.32±0.14 and 1.28±0.15; HR response to deep breathing test were 25.36±3.90, 18.82±3.35 and 15.96±3.54 beats/min; 30th:15th ratio in standing test were 1.100.06, 1.05±0.03 and 1.04±0.02 in 21- 30, 51-60 and 61-70 years age groups respectively. All the 3 parameters were significantly lower in both elderly groups compared to that of control adults (p<0.001) Again, HR response to deep breathing was significantly lower in 61-70 years age group compared to that of 51-60 years age group. Valsalva ratio and 30th:15th ratio were also lower in 61-70 years age group than that of 51-60 years group but the differences were not statistically significant. All the 3 parameters were negatively correlated with age which were statistically significant. Conclusion: From this study it may concluded that aging process substantially impaired cardiovascular parasympathetic nerve functions.