The cardiac output and renal plasma flow were simultaneously determined by external monitoring method with ^(125)I-serum albumin and ^(131)I-Hippuran in 21 cases of normal subjects and 29 cases with essential hypertension. The cardiac and renal hemodynamic changes influenced by administration of chlorothiazide, reserpine and Aldomet^(®) in hypertensive patients were evaluated.
Following were the results:
1. In 21 cases of normal control in the present study, the following data were obtained: plasma volume, 49.5±2.4ml/kg; cardiac output 5072±374 ml/min.; cardiac index, 3021±298 ml/min./㎡ strovolume, 81±9 ml/beat; stroke index, 49±7 ml/ beat/㎡ total peripheral resistance, 2495±656 dynes sec. cm-5m2 and renal plasma flow, 582±60 ml/min. /1.73㎡. The measurement of cardiac output and renal plasma flow using, radioisotopes was a simple and accurate method.
2. In 29 cases of hypertensive patients, the plasma volume, cardiac output, cardiac index, stroke index and renal plasma flow tended to be slightly low compared to normal control but they were statistically insignificant, while total peripheral resistance was markedly high.
3. In both normal control and hypertensive group, the significant correlat o i was found between plasma volume, cardiac output or cardiac index and renal plasma flow. Especially it was highly and statistically significant between plasma volume and renal plasma flow in hypertensive group, cardiac output and renal plasma flow in hypertensive group and cardiac index and renal plasma flow in both groups.
4. In essential hypertension, a short term administration of chlorothiazide resulted in the marked reduction of plasma volume, cardiac output and renal plasma flow, and the reduction of them was considered to be important role in antihypertensive mechanism of chlorothiazide.
5. The long term oral administration of reserpine in hypertensive group-showed no significant changes of plasma volume, cardiac output, total peripheral resistance and renal plasma flow except for mild bradycardia, while acute administration of reserpine revealed marked reduction of cardiac output which
was statistically significant. Antihypertensive action of reserpine, especially in acute administration, was found be be related to the reduction of cardiac output.
6. No significant changes in cardiac output and renal plasma flow were observed after oral admistration of Aldomete^(®). It was considerable that the reduction of total peripheral resistance played an important role in antihypertensive action of Aldomet^(®).
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