Hiroshi WATANABE

Adrenal catecholamines were determined in Wistar Kyoto rats (WKY), and stroke-prone and stroke-resistant spontaneously hypertensive rats (SHRSP, SHR) treated with hyperbaric oxygen for 90 minutes daily from 6 to 13 weeks of age. The animals were divided into 5 groups. Group I (control group), was handled under the same conditions as pressure-treated groups II and III, but with ambient oxygen pres-sure and concentration. Group II (pressure-control group), was treated with 2 atmospheric absolute pressures (ATA) of air without any oxygen provided. Group III (high-oxygen group), was exposed to 2 ATA under the environment of air saturating oxygen. Group IV (antihypertensive group), was treated with hydralazine. Group V (adrenalectomized group), was given 1 % NaCI solution and bilateral adrenalectomy. The average contents of adrenal norepinephrine of SHR and of SHRSP in Group I were greater (p <0.05-p <0.001) than those of the WKY in Group I. A similar tendency was also observed for the content of adrenal epinephrine. The average concentrations of adrenal epinephrine and norepinephrine of SHR and SHRSP in Group II and III were significantly (p <0.05-p <0.001) greater than those of the respective rats in Group I, but no significant differences were noted in the blood pressure between pressure-treated groups (II, III) and the control group (I). Adrenalectomized SHR, SHRS