Pattern of blood pressures among high and low altitude residents of southern Saudi Arabia

The patterns of blood pressures and their correlates in 499 Saudi nationals aged 10-72 years living at high altitude (3150 m above sea level) and 594 Saudi nationals aged 10-76 years living at low altitude (500 m above sea level) were prospectively studied. The average BPs were significantly higher in highlanders compared with lowlanders. In both high and lowland residents the BPs rose with age although males in both groups showed a drop in both SBP and DBP beyond the age of 50 years. Hypertension (> 160/95 mmHg) was not detected among lowlanders and only 1.4% of all highlanders were found to be hypertensive. These differences in BPs are attributed to the significantly higher body mass index values and packed cell volume levels in the highlanders.

Acute and chronic effects of progesterone and prolactin on renal function in the rat

The renal effects of acute and chronic progesterone and prolactin administration were investigated in rats. Acute progesterone treatment caused a reduced urinary potassium excretion compared to controls (0.80 +/- 0.03 vs. 1.30 +/- 0.04 mumole min-1; P less than 0.01). No other renal changes were apparent. Acute prolactin administration produced no significant changes in renal function. Chronic progesterone treatment reduced urinary potassium output by increasing tubular reabsorption. Absolute reabsorption (mumole min-1) for controls was 4.70 +/- 0.42 and for progesterone treatment, 6.40 +/- 0.57 (P less than 0.05 comparing the two). No other renal changes were apparent. Animals made pseudopregnant by chronic prolactin administration showed a significant (16%) elevation in glomerular filtration rate, similarly enhanced fluid and solute reabsorption, and a significant (16%) increase in proximal tubule length. This would imply a role for prolactin in early rat pregnancy and pseudopregnancy when similar renal changes are evident and circulating hormone levels high.