Abstract
Many investigators have noted increased pressor (or diminished depressor) substances in the blood of patients with hypertension. 1 - 4 Others frequently employing similar methods, have failed to find them. 5 - 9 We have used the denervated rabbit's ear preparation as described by Pissemski 10 and modified by Katz 11 to compare the effect of blood of persons with hypertension and subjects with normal blood pressures. This preparation has been found to be sensitive to known pressor substances in high dilutions (epinephrine 1 to 100,000,000 and pitressin 1 to 150,000), and has an important advantage in that whole undiluted relatively unchanged blood plasma may be used. In the early experiments the inflow pipette was connected to a Mariotte bottle. Subsequently we found a constant volume pump to be more satisfactory.
The perfusion was started with Tyrode's solution and followed with unheated plasma alternating between blood from normal and hypersensitive individuals and noting the changes in pressure with constant inflow. Either citrate or heparin was used as anticoagulant. Generally about one hour elapsed between the time of withdrawal of the blood and the beginning of the experiment.
Eighteen patients with hypertension have been studied. These comprise 8 with benign hypertension, 2 with malignant hypertension, 7 in various stages of glomerulo-nephritis and one with polycystic kidney disease. The effect of the plasma as compared with that of the normal control is summarized in the table.
In 16 cases there was a depressor or no effect and in only 2 instances was there a definite pressor effect of the blood from the subject with hypertension over that from the individual with normal blood pressure. These changes could not be attributed to variations in viscosity or surface tension, since these properties varied only slightly and in no consistent direction.
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