1. Electrolyte transport characteristics were examined in erythrocytes from 13 normal men and from two groups of women: (i) taking combined oral contraceptive preparations (O/C, n = 10), and (ii) ovulatory women (non-O/C, n = 10) pre- and post-ovulation, at the same time intervals (days 7–10 and days 15–18) during a menstrual cycle. 2. With rubidium ( 86 Rb + ) used as a potassium analogue, co-transport (ouabain-resistant, fruse-mide-sensitive 86 Rb + influx) values were found to be lowest in non-O/C women (28 ± se 2.5 nmol h −1 10 −9 cells) and highest in men (56 ± 5.7, P < 0.001), with results between the two in women taking O/C (42 ± 4.2, P < 0.05 vs men, P < 0.01 vs non-O/C). Passive 86 Rb leak (frusemideand ouabain-resistant) was significantly lower in men (13 ± 1.6 nmol h −1 10 −9 cells) than in both groups of women (non-O/C 29 ± 1.8, P < 0.001; O/C 25 ± 1.2, P < 0.001). There was no cyclical variation within either group of women. 3. Maximum ouabain binding (number of Na + ,K + -ATPase units) was the same in all groups. Na + ,K + -ATPase activity, as determined by ouabain-sensitive 86 Rb influx, was the same in men and non-O/C groups, but was significantly suppressed in O/C compared with both men ( P < 0.01) and non-O/C women ( P < 0.05). 4. The differences found were not due to alterations in either progesterone or aldosterone, but could represent an androgenic effect in vivo of the 19-nortestosterone derivatives in combined oral contraceptive preparations.
1. Haemodynamic and left ventricular variables were determined by M-mode echocardiography in 21 normotensive and 36 hypertensive patients during the last trimester of pregnancy. 2. Blood pressure of hypertensive patients was lowered by bed rest only, or by oxprenolol or methyldopa, but remained elevated. 3. Cardiac output was raised in the last trimester of pregnancy in both normotensive and hypertensive patients. 4. Left ventricular mass was increased in normal pregnancy, but displayed an exaggerated increase in hypertensive patients. 5. Total peripheral resistance was inappropriately elevated in hypertensive pregnancy, except in the oxprenolol-treated group. 6. There was no reduction in heart rate or cardiac output in the group treated with β - adrenoreceptor blocking agents. These factors, in combination with normal peripheral resistance, may contribute to the improvement in foetal outcome described in maternal hypertension of pregnancy treated with oxprenolol.