C-type natriuretic-peptide-potentiated relaxation response of gastric smooth muscle in streptozotocin-induced diabetic rats

AIM: To study the sensitivity of gastric smooth muscle to C-type natriuretic peptide (CNP) in streptozotocin (STZ)-induced diabetic rats. METHODS: The spontaneous contraction of a gastric smooth muscle strip was recorded by using physiological methods in rats. The expressions of CNP and natriuretic peptide receptor-B (NPR-B) in gastric tissue were examined by using immunohistochemistry techniques in the diabetic rat. RESULTS: At 4 wk after injection of STZ and vehicle, the frequency of spontaneous contraction of gastric smooth muscle was significantly reduced in diabetic rats, and the frequency was decreased from 3.10 ± 0.14 cycle/min in controls to 2.23 ± 0.13 cycle/min (n = 8, P < 0.01). However, the amplitude of spontaneous contraction was not significant different from the normal rat. CNP significantly inhibited spontaneous contraction of gastric smooth muscle in normal and diabetic rats, but the inhibitory effect was significantly potentiated in the diabetic rats. The amplitudes of spontaneous contraction were suppressed by 75.15% ± 0.71% and 58.92% ± 1.32% while the frequencies were decreased by 53.33% ± 2.03% and 26.95% ± 2.82% in diabetic and normal rats, respectively (n = 8, P < 0.01). The expression of CNP in gastric tissue was not changed in diabetic rats, however the expression of NPR-B was significantly increased in diabetic rats, and the staining indexes of NPR-B were 30.67 ± 1.59 and 17.63 ± 1.49 in diabetic and normal rat, respectively (n = 8, P < 0.01).CONCLUSION: The results suggest that CNP induced an inhibitory effect on spontaneous contraction of gastric smooth muscle, potentiated in diabetic rat via up-regulation of the natriuretic peptides-NPR-B-particulate guanylyl cyclase-cyclic GMP signal pathway.

Correlations among Persistent Viral Infection,Heart Function and Chinese Medicine Syndromes in Dilated Cardiomyopathy Patients

Objective：To investigate the correlations among persistent viral infection,heart function and Chinese medicine（CM） difined-syndromes in patients with dilated cardiomyopathy（DCM）.Methods：Fifty patients with DCM in the First Affiliated Hospital of Zhejiang Chinese Medical University from October 2009 to December 2011 were selected as the research subjects,and 30 healthy people were simultaneously selected as the normal control group to detect persistent viral infections after admission.The CM syndrome type and grade of heart function were then evaluated.The expression level of Coxsackie adenovirus receptor（CAR） was detected using the flow cytometry（FCM） technique,coxsackie virus RNA（CVB-RNA） using reverse transcription polymerase chain reaction（RTPCR）,and the plasma brain natriuretic peptide（BNP） level with a Triage meter plus diagnosis instrument.Finally,the parameters such as left ventricular end diastolic diameter（LVEDd） and left ventricular ejection fraction（LVEF） were measured by ultrasonic cardiogram.Person correlation analysis was used for measured data,Spearman correlation analysis for rating data,and the Chi-square test for numerical data.Results：CVB-RNA was positive in 22 patients（44%） with DCM,while only 6 cases（20%） were CVB-RNA-positive in the normal control group,with a significant difference between the two groups（P〈0.01）.The expression level of CAR was significantly elevated in the DCM group compared with the normal control group（P〈0.01）.In CVB-RNA-positive patients（22 cases）,the expression level of CAR was significantly higher than in CVB-RNA-negative patients（28 cases;P〈0.01）.In the DCM patients,there was a positive correlation between the CAR expression and the BNP level（r=0.34,P〈0.05）,while no significant difference was found between the CAR expression and the LVEF and LVEDd（r=-0.32,0.30,P〉0.05）.There was no clear correlation between virus infection and the CM syndrome types in DCM patients（r=-0.22,P〉0.05）.According to the sequence of syndrome types：phlegm → qi deficiency → blood stasis → hydroretention with asthenic yang（from low to high）,a positive correlation was existed between the BNP levels and CM syndrome types（r=0.139,P〈0.05）.Conclusion：The expression of CAR on the surface of white cells could be used to detect persistent viral infection.The expression level of CAR and heart function in DCM patients were highly correlated.The expression level of BNP may serve as an objective index for differentiating CM syndromes for patients with DCM.