Oestradiol-induced hypotension in spontaneously hypertensive rats: putative role for intracellular cations, sodium-potassium flux and prostanoids.
1. The effect of oestradiol alone and in combination with indomethacin on blood pressure, erythrocyte cation concentration and Na(+)-K+ flux has been studied in adult female normotensive and spontaneously hypertensive rats. 2. Oestradiol alone resulted in a significant decrease in blood pressure in spontaneously hypertensive rats (from 165.3 +/- 3.9 to 146.4 +/- 2.7 mmHg, P less than 0.001), whereas it induced a significant increase in normotensive rats (from 111.8 +/- 1.8 to 124.1 +/- 3.6 mmHg, P less than 0.001). When indomethacin and oestradiol were administered simultaneously or when indomethacin was given alone, no change in blood pressure occurred in spontaneously hypertensive rats (158.6 +/- 6.9 and 159.8 +/- 6.2 mmHg, respectively). 3. The fall in blood pressure induced by oestradiol in spontaneously hypertensive rats was associated with significant reductions in erythrocyte K+ concentration (from 127.4 +/- 1.2 to 116.9 +/- 1.7 mmol/l of cells, P less than 0.001), in erythrocyte Na+ concentration (from 14.3 +/- 0.8 to 13.0 +/- 0.6 mmol/l of cells, P less than 0.02), in ouabain-sensitive erythrocyte Na+ flux (from 17.8 +/- 0.3 to 16.0 +/- 0.4 mmol h-1 (l of cells)-1, P less than 0.01) and in ouabain-sensitive erythrocyte K+ flux (from 11.4 +/- 0.2 to 10.4 +/- 0.2 mmol h-1 (l of cells)-1, P less than 0.01). No change in blood pressure, erythrocyte cation concentration or Na(+)-K+ flux occurred when oestradiol and indomethacin were given together or when indomethacin was administered alone.(ABSTRACT TRUNCATED AT 250 WORDS)
Stonier
C
C
School of Postgraduate Medicine and Biological Sciences, University of Keele, Stoke-on-Trent, U.K.
Bennett
J
J
Messenger
E A
EA
Aber
G M
GM
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D004912:Erythrocytes / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006400:Hematocrit; D007022:Hypotension / Q000139:chemically induced*; D007213:Indomethacin / Q000494:pharmacology; D011188:Potassium / Q000097:blood*; D051381:Rats; D011918:Rats, Inbred SHR; D012083:Renin / Q000097:blood; D012964:Sodium / Q000097:blood*; D000254:Sodium-Potassium-Exchanging ATPase / Q000502:physiology
D004958:Estradiol; D012964:Sodium; D012083:Renin; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D007213:Indomethacin