Objective To explore the interaction between nitric oxide (NO) and intracerebroventricular (icv.) substance P (SP) in cardiovascular regulation in anesthetized rabbits.Methods Rabbits anesthetized with urethane were intracerebroventricularly given SP (7 46?nmol),while artificial cerebrospinal fluid were given to controls.Cardiovascular responses induced by SP including heart rate (HR),mean arterial blood pressure (MAP),left ventricular systolic pressure (LVSP),left ventricular end diastolic pressure (LVEDP),the maximum velocity of ascending or descending in intraventricular pressure ( ±d p /d t max ) and the maximum shortening velocity (Vpm)of myocardial contractile element were recorded in computer with BL?310 biosoftware,and the content of NO in cerebrospinal fluid (CSF)were determined by nitrate reductase chemiluminescence in rabbits injected intracerebroventricularly with SP.Results (1)icv.SP induced significant increases of HR,MAP,LVSP,LVEDP,+d p /d t max ,-d p /d t max ,Vpm and the decreases in levels of NO in intracisternal CSF 10?min after injection.Conclusions (1)icv.SP can produce positively inotropic response in myocardium and increase arterial pressure in intact rabbits.(2)Decreased NO may be related to the cardiovascular responses to icv. SP. |
