ABSTRACT
BACKGROUND: Dihydrolycorine (DL) can inhibit the peripheral release of catecholamine from sympathetic nerve ending and block α, β adrenalinergic receptor. It has multiple pharmacological actions, such as vascular dilation, hypotension, anti-hypoglycemia and anti-ischemia.OBJECTIVE: To investigate the selective effect of DL on basilar artery,thoracic aorta and ventricular papillary muscle of rabbit by means of observing the vasoconstriction induced by noradrenaline bitartrate and KCl.DESIGN: Observation of comparative experiment.SETTING: Pharmacological Department of Yunyang Medical College.MATERIALS: This study was carried out at Pharmacological Department of Yunyang Medical College between March and July 2001, and 46 adult healthy New Zealand rabbits were selected.METHODS: New Zealand rabbits were put to death by intravenous injection of 10 mL air from the vein of aural edge, and soon after death, brain,thoracic aorta and heart were obtained. Basilar artery and thoracic aorta was linked into 4.0-5.0 mm vascular rings; meanwhile, ventricular papillary muscle were separated and connected with tension transducer. Obserdose of noradrenaline bitartrate or KCl: Sub-maximal constriction of thoracic aorta was induced by 0.1 mmol/L noradrenaline bitartrate or W60 mmol/L KCl, and when constriction curve became stable, DL or nimodipine of different dosage was added. Basilar artery was exposed to 0.1 mmol/L noradrenaline bitartrate or 60 mol/L KCl, and rinsing fluid was changed once every 20 minutes and thrice in all when vasocontratcion reached the peak level, then different dosage of DL or nimodipine was added 20 minutes later, and the changes of vasoconstriction curve due to administration of single dose of noradrenaline bitartrate or KCl were obconstriction of ventricular papillary muscular induced by electro-stimulation: Electro-stimulation was used to stimulate the ventricle papillary muscular synchronized constriction with the frequency of once per second,wavelength of 3 ms and threshold voltage of 120%; when constriction curve became stable, DL or nimodipine was administered in a accumulative way.ence of DL or nimodipine on the half-effective concentration of noradrenaline bitartrate or KCl that contributed to the vascular ring constriction of rabbit.RESULTS: Basilar artery, thoracic aorta and ventricular papillary muscle Resting tension of basilar artery was increased by DL but decreased by niof basilar artery and thoracic aorta induced by noradrenaline bitartrate and KCl can be relaxed by DL in a dose dependant manner, and the half-effective concentration was (6.69±3.12)×10-4, (3.41±1.52)×10-3mmol/L for basilar artery, and (1.49±0.59)×10-3, (2.91±0.99)×10-3 mmol/L for thoracic aorta, displaying stronger inhibition on the constriction of basilar artery induced by noradrenaline bitartrate than on the contraction induced by KCl.On the contrary, nimodipine showed stronger depression on KCl-induced constriction than on the constriction induced by noradrenaline bitartrate.ventricle papillary muscular induced by electro-stimulation in a dose-dependant manner, and the half-effective concentration of DL on the contraction of ventricle papillary muscle induced by electro-stimulation was significantly higher than that induced by noradrenaline bitartrate.CONCLUSION: DL displays obvious selective effect on basilar artery of rabbit, the possible existence of constrictive α1 receptor subtype and dilating β receptor on basilar artery might be correlated with the selective function of DL, which benefit, for the improvement of blood supply in the ischemic region.
ABSTRACT
Hemodynamic study of L-THP in anaesthetized rats showed that 6 mg/kg iv decreased only blood pressure (BP) significantly, and decreased left ventricular pressure ( LVP ) temporarily. At the dose of 18 mg/kg, L-THP lowered the BP, LVP, ? ( dP/dt ) max, ( dP/dt ) P-1 and HR. But the degrees o?diminutions of BP were greater than that of cardiac contractility. The inhibitory percentage of L-THP on DAP was greater than that of SAP. In addition, the extent of decrease of DAP was shown dose dependently. The results suggest that L-THP reduces the peripheral vessel resistance, and it inhibits the cardiac contractibility in high dosage.
ABSTRACT
The antagonistic effects of L-THP, Ver and Pap to contraction of isolated guinea pig trachea preparations induced by BaCl2 10-3mol/L ,KC1 3?10-2mol/L, 5-HT 2?10-5mol/L, Ach 2?10-5mol/L and His 2? 10-5mol/L were studied.The antagonistic effects of L-THP were different from Ver and Pap. The IC50 value of L-THP for contraction induced by BaCl2, KC1, 5-HT and His was 3 .5? 10-5mol/L , 4.5 ? 10-5mol/L , 2.5?10-3 mol/L and 8.9? 10-5mol/L respectively. It was showed that sensibility of several agonists to inhibition by L-THP was correlated with dependence of extracellular Ca2+. The potencies of L-THP on anti-KCl and anti-5-HT actions were similar. The results suggested that LTHP possesses anti-calcium and anti-5-HT action on guinea pig trachea.