Effect of long-term nitrous oxide inhalation on the cardiac function in rats / 西安交通大学学报(医学版)

ABSTRACT

Objective To observe whether or not long-term inhalation of nitrous oxide can affect the cardiac function in rats. Methods Sprague-Dawley rats of either sex were randomly divided into four groups. Group A inhaled common air for 50 days as control; Group B inhaled 500mL/L N_2O for 15 days, two hours every day; Group C inhaled 500mL/L N_2O for 30 days, two hours every day; Group D inhaled 500mL/L N_2O for 50 days, two hours every day. Float glass intracellular microelectrode recording technique was used for observation of the duration (MAPD_(90), MAPD_(50) and MAPD_(20)) and amplitude of action potentials (APs) of left ventricular muscle cells in vitro. Angiotensin-2 (Ang-2) and eNOS were detected by immunohistochemical technique. Results ① Compared with that in Group A, the Aps duration of left ventricular muscle cells (MAPD) in Group B had no significant change while the MAPDs in Group C and Group D were extended significantly. There were no significant differences among the four groups in Aps amplitude. ② The expression of Ang-2 did not differ significantly between Group B and Group A. The expression level was higher in Group C and D than in Group A. ③ The expression level of eNOS was significantly lower in Group C and D than in Group A (P<0.05). Conclusion Long-term inhalation of N2O can significantly affect the cardiac function in rats, which may be related to higher expression of AngⅡin the heart induced by the long-time excitation of sympathetic nerves.