[Modification of vasoconstriction in ischemically stressed and extracorporeally perfused dog kidneys by alpha adrenergic blockade with phenoxybenzamine]

Renal vasoconstriction was induced in mongrel dogs by clamping the pedicle for 30 min. After reestablishing the renal blood flow for 10 min, the kidneys were removed and flushed for 15 min with cooled Euro-Collins solution. As to estimate the spasmolytic effect of alpha adrenergic blockade with phenoxybenzamine (2 mg/kg) the left or right kidney was first flushed without post-ischemic blockade (control), whereas before nephrectomy of the remaining kidney the dogs received phenoxybenzamine. This was injected intravenously either immediately after the ischemia period maintaining the physiologic blood pressure by volume substitution (group 1) or without volumetric stabilization of the pressure (group 2) or 30 s before the harvesting procedure (group 3). The results showed that pretreatment with phenoxybenzamine in all groups caused a significant reduction of the renal vascular resistance and an improved microcirculation of the Collins solution during the isolated kidney perfusion as compared to the untreated kidneys. The vasodilatatoric effect markedly depends on the blood pressure during the reflow interval and on the time of bolus application before nephrectomy.