LONG-TERM EFFECTS OF PENTOBARBITAL-ANESTHESIA ON THE ATRIAL-NATRIURETIC-PEPTIDE SYSTEM IN RATS

A long-term effect of pentobarbital treatment on the storage and relea se of atrial natriuretic peptide (ANP) was investigated in rats. The e xperimental group was treated with pentobarbital (50 mg/kg, ip), and t he control group was injected with the vehicle only. They were used on e week after the treatment. Male and female rats were used separately to see if there exists a sex difference in the response to pentobarbit al. In male rats, the plasma ANP measured in a conscious state was sig nificantly higher in the experimental group than in the control. The A NP content as well as the number of specific granules in the atrial ti ssue was significantly lower in the experimental group. In response to extracellular volume expansion (VE), amounting up to 5% of the body w eight over 30 min, while the plasma ANP increased in the control, it d id not significantly change in the experimental group. Urinary respons es to the exogenous infusion of ANP did not differ in magnitude betwee n the two groups. In female rats, neither the plasma level nor the atr ial content of ANP (or the atrial granularity) was different between t he experimental and control groups. Nor did the increase of plasma ANP in response to VE differ in magnitude between the two groups in femal e rats. These results indicate that pentobarbital may have a long-term effect on the storage and release of ANP.