ABSTRACT
Aim To investigate the preventive effect of Guizhi decoction on cardiac sympathetic sprouting induced by 4-Methylcatechol (4-MC) . Methods The rat models of cardiac sympathetic sprouting were in-duced by 10 mg · L-1 4-MC ( 10μg · kg-1 body weight, i. p. ) . Guizhi decoctions ( with different pro-portion between Ramulus Cinnamomi and Radix Paeon-iae Alba, 1 : 1, 1 : 2 and 2 : 1) and metoprolol were administered to the rats. Heart rate and electrocardio-gram ( ECG ) were observed, the content of norepi-nephrine (NE), growth associated protein (GAP-43), tyrosine hydroxylase ( TH ) and acetylcholine transfer-ase enzyme ( CHAT) in myocardial homogenate of left ventricular and right atrial were determined by ELISA method, and immunofluorescence assay was used to observe cardiac nerve sprouting and sympathetic distri-bution. Results 4-MC caused cardiac sympathetic sprouting and parasympathetic was not influenced. Heart rate of the model group was improved significant-ly and higher than that of the other groups . Compared with the model group, the content of NE, GAP-43 and TH in left ventricle and right atrium of the metoprolol group and Guizhi decoction group were decreased( P<0.05 ) , and the immunofluorescence result showed that the distribution of TH positive nerve was reduced sig-nificantly(P<0.05). It was demonstrated that Guizhi decoction of the proportion between Ramulus Cinnamo-mi and Radix Paeoniae Alba 1 : 1 and 1 : 2 had the best efficacy, which was similar to the efficacy of meto-prolol. Conclusion Guizhi decoction ( with the pro-portion between Ramulus Cinnamomi and Radix Paeon-iae Alba 1 : 1 and 1 : 2 ) effectively inhibits the cardi-ac sympathetic sprouting induced by 4-MC.
ABSTRACT
PurposeTo study the effects of intravenous propranolol and metoprolol on cardiorespiratory and metabolic responses to exercise. MethodsTwo groups of anaesthetized dogs (sodium pentobarbital, 33 mg/kg) were studied at rest and moderate exercise (induced by electrical stimulation) before and after metoprolol (0.4 mg/ Kg, n = 7) or propranolol (0.2 mg/kg, n = 10). Haemodynamic, metabolic and respiratory variables were measured. ResultsThere was a decrease in heart rate both at rest and during exercise after metoprolol and propranolol administration. The cardiac output, stroke volume and peripheral vascular resistance presented decreased responses to exercise after both drugs. O2 consumption and CO2 production were not altered signifcantly at rest but increased in a lesser degree during exercise. Propranolol administration reduced ventilation during rest and exercise, although the ventilatory response to exercise remained the same. Metoprolol administration did not affect ventilation at rest but reduced the ventilatory response to exercise leading to an increase of the PaCO2 Conclusion Propranolol and metoprolol effects on cardiovascular and metabolic variables measured at rest and during exercise were the same. The ventilatory effect with metoprolol administration was different from the observed with propranolol