RENAL-ARTERY VASOMOTION - IN-VIVO ASSESSMENT IN THE PIG WITH INTRAVASCULAR DOPPLER

Intravascular Doppler is widely used for experimental studies in the c oronary circulation. We designed this study to assess baseline bloodfl ow and arteriolar resistance in the porcine renal circulation and to s tudy the vasomotor responses of vasoactive drugs. In anesthesized pigl ets (n = 15), renal arterial diameter was measured with quantitative a ngiography and blood flow velocity with a Doppler wire (Cardiometrics) . Bloodflow and resistances were calculated at baseline and after inje ction of vasoactive drugs (isosorbide dinitrate, papaverine). This all owed us to determine the renal bloodflow reserve (the capacity of the kidney to augment basal bloodflow). Injection of isosorbide dinitrate was associated with an increase in average peak velocity of 64% (P < 0 .01) and a small (from 4.5 to 4.74, P < 0.01) but significant increase in renal artery diameter, resulting in an increase in bloodflow of 82 % (P < 0.01) and a decrease in arteriolar resistance of 46% (P < 0.01) . Bloodflow returned to baseline (4.76 +/- 1.48 mL/s) approximately 5 min after isosorbide injection. Average Peak Velocity increased almost twofold after papaverine injection (60 +/- 10 to 108 +/- 24 cm/sec, P < 0.01). There was a significant (P < 0.01) increase in arterial bloo dflow of 96% in the right and 79% in the left renal artery after injec tion of papaverine with a corresponding significant (P < 0.01) decreas e in arteriolar resistance of 49% in the right and 44% in the left ren al artery. Using a combination of quantitative angiography and intrava scular Doppler allows easy measurement of baseline renal blood flow an d of the effects of vasodilator drugs on bloodflow and resistance. The results show that a vasodilatator reserve exists in the renal circula tion but is less marked than that reported in the coronary circulation . (C) Elsevier, Paris.