A nitrosyl meso-tetrakis[4-(sodium sulfonato)phenyl]porphyrin manganese complex (TPPSNa- Mn-NO) was synthesized as a NO donor and its pharmacological effects were investigated. The NO-relea- sing property of TPPSNa-Mn-NO in aqueous was studied by diazotization at room temperature. The relaxation of TPPSNa-Mn-NO was investigated on isolated rabbit aorta pectoralis circle. The systolic blood pressure, diastolic blood pressure and heart rates of rats were investigated before and after drug administration. The NO-releasing ratio of TPPSNa-Mn-NO was 70.86%. TPPSNa-Mn-NO shifted methoxamine cumulative dose-response curves rightward im-paralleling a group reduced the Max, and the reduced percentage was 30.2%. For the blood pressure of rats began to decrease at the time of 5 min after the administration, the blood pressure of rats reached the minimum at the time of 30 min, then increased slowly, and finally, ap-proached the normal blood pressure at 120 min, but was still lower than that before the administration. For the control group, the blood pressure of the rats was not changed after employing the normal salined. For the treatment TPPSNa-Mn-NO could decrease the blood pressure slowly and lastingly, but had no effect on heart rates, anapnea and electrocardiography. Perhaps it would be used as an ideal prolonged hypotensive drug.

Key words: NO donor, isolated vascular circle, depressurizati, TAPPSNa-Mn-NO