LONG-TERM MEASUREMENT OF ARTERIAL BLOOD-PRESSURE IN CONSCIOUS MICE

This study describes a technique for the direct daily measurement of a rterial blood pressure, sampling of arterial blood, and continuous int ravenous infusion in free-moving, conscious, Swiss-Webster mice. Cathe ters were chronically implanted in the femoral artery and vein, tunnel ed subcutaneously, exteriorized at the back of the neck in a lightweig ht tethering spring, and attached to a swivel device at the top of the cage. Time-control experiments (n = 8) demonstrated stable values of mean arterial pressure (MAP, 116 +/- 1 mmHg) and heart rate (HR, 627 /- 21 beats/min) for up to 35 days after catheter implantation. It was further observed that restraining mice (n = 7) increased MAP by 10 +/ - 3 mmHg and HR by 78 +/- 8 beats/min from the values observed under f ree-moving conditions. To demonstrate the chronic use of the venous ca theter, intravenous infusion of N-G-nitro-L-arginine methyl ester (L-N AME, 8.6 mg.kg(-1).day(-1), n = 6) for 5 days significantly increased MAP from 117 +/- 4 to 131 +/- 4 mmHg without altering HR. In a final g roup of mice (n = 5), oral L-arginine (2% in drinking water) increased plasma arginine concentration from 90 +/- 7 to 131 +/- 17 mu M and pr evented L-NAME hypertension. These experiments illustrate the feasibil ity of long-term intravenous infusion, direct arterial blood pressure measurements, and arterial blood sampling in conscious mice.