Epstein M

“No man's land” of the renal vasculature: An arteriographic and hemodynamic assessment of the interlobar and arcuate arteries in essential and accelerated hypertension☆

Abstract A highly significant correlation has been demonstrated between abnormalities at the interlobar and arcuate artery level in selective renal arteriograms of sixty-six patients with essential hypertension and several clinical indices including the age of the patient and the duration, severity and presence of complications of hypertension. The vascular abnormality at this level also shows a significant correlation with intrarenal hemodynamics assessed by 133 Xe washout and renal function. The hemodynamic and arteriographic changes suggest the presence of focal cortical areas of decreased perfusion in many patients, which may well contribute to the progress and severity of the hypertension. The arterial changes at this level have also been shown to progress with age in a normal population. This age-related change is potentiated in hypertensive subjects.

Renin secretion in essential and accelerated hypertension

Abstract The simultaneous determination of renal blood flow with 133 Xe washout and renin activity in arterial and renal vein blood has allowed calculation of net renin secretion from the kidneys of twenty-seven patients with essential and accelerated hypertension. Renin secretion was very low in patients with uncomplicated essential hypertension in whom renal hemodynamics and selective renal arteriograms were normal. A significant increase in renin secretion was found in patients with essential hypertension complicated by moderately severe small artery disease in the kidney and reduced renal blood flow. The observation that patients with small artery disease involving the kidney had both a significant increase in renin secretion rate and significantly higher blood pressure levels raises the possibility that the increased renin secretion contributed to the severity of the hypertension in these patients. Patients with malignant hypertension had a very large increase in the rate of renin secretion.

Renal Vascular Response to Salt Restriction in Normal Man Evidence Against Adrenergic Mediation

The role of the sympathetic nervous system in the renal vasoconstriction induced by sodium restriction has been assessed in normal man in balance on a 10-mEq sodium intake. Renal blood flow was measured with radioxenon injected into the renal artery. Phentolamine infused into the renal artery at rates of up to 3 mg/min did not increase net renal perfusion or alter its intrarenal pattern. That dose of phentolamine was at least 30 times the threshold for significant blockade of the renal vascular effects of a large dose of epinephrine injected intra-arterially. The results suggest strongly that neither circulating catecholamines nor the sympathetic nerves play a central role in the renal vascular response to salt restriction in normal man.

The Pattern of the Renal Vascular Response to Epinephrine in Man

Summary The effect of epinephrine injected into the renal artery has been studied as a model for the assessment by angiography and xenon washout of the control and relative responsiveness of the renal cortical vasculature to such stimuli in man and to ascertain whether a quantitatively significant shunt mechanism can be demonstrated in the human kidney. The findings suggested a dominant sensitivity of the cortical vasculature and rule out the presence of a quantitatively significant shunt mechanism in this setting. The pattern of recovery from the effects of epinephrine suggests that patchy areas in the cortex recover a normal rate of perfusion while other areas remain extremely vasoconstricted. This pattern of perfusion appears to be characteristic of the kidney in a large number of clinical situations.