Sequential changes in urinary catecholamine in the transition from benign to malignant hypertension in rats

The sequential changes in 24-hour urinary norepinephrine (NE) and epinephrine (E) excretion levels were measured in spontaneously hypertensive rats (SHR) that received deoxycorticosterone acetate (DOCA) and 1% NaCl drinking water. These were compared with those from control SHR and similarly treated Wistar-Kyoto rats (WKY). Blood pressure, NE and E increased progressively in DOCA-SHR group, and NE (2392 +/- 94 vs. 998 +/- 49 ng/day) and E (250 +/- 21 vs. 116 +/- 6 ng/day) exceeded twice that of the control SHR group in the sixth week of DOCA treatment. In WKY rats, NE (1372 +/- 48 vs. 968 +/- 37 ng/day) and E (147 +/- 9 vs. 121 +/- 7 ng/day) levels were significantly higher in rats given DOCA than those in control group in the sixth week of the treatment, but were not so remarkably high as in DOCA-SHR group. A histological examination of DOCA-SHR kidneys revealed fibrinoid necrosis in the vascular walls. These data suggest that sympathoadrenal activity plays an important role in the development of malignant hypertension in DOCA-SHR group.