Increased renal tubular Na-K-ATPase activity in Milan hypertensive rats in the prehypertensive period.
Milan hypertensive (MSH) rats develop hypertension around the 3rd-4th week of life and exhibit increased Na-pump activity in adulthood. The present study was performed to evaluate whether or not hypertension is preceded by an increase in Na-K-ATPase activity. Total and ouabain-sensitive ATPase activities were studied in single microdissected medullary thick ascending limb of Henle (mTAL) tubules from MHS, Milan normotensive (MNS) and Sprague-Dawley (SD) rats at 22-24, 26-28 and 45-60 days of age. Data are given as mean +/- SEM. Total and Na-K-ATPase activity exhibited a developmental pattern in MHS, MNS and SD rats. At 22-24 days no difference was seen between MHS and MNS animals. At 26-28 days MHS had a higher total and Na-K-ATPase activity than MNS (3031 + 171 vs 2471 + 178 pmol phosphate/mm tubule per hour, P less than 0.05; 2289 + 205 vs 1653 + 151, n = 10, P less than 0.05). At this age there was still no difference in mean arterial blood pressure (88 + 4 vs 86 + 3 mm Hg, n = 15). Adult MHS rats had higher blood pressure (140 + 9 vs 112 + 8 mm Hg, P less than 0.001) and higher total (3544 + 136 vs 2718 + 215 pmol phosphate/mm tubule per hour, n = 10, P less than 0.01) and Na-K-ATPase activity (2670 + 99 vs 1942 + 217 pmol phosphate/mm tubule per hour, n = 10, P less than 0.05) than adult MNS rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Melzi
M L
ML
Department of Paediatrics, University of Milan, Italy.
Syrén
M L
ML
Assael
B M
BM
Sereni
F
F
Aperia
A
A
D000818:Animals; D001794:Blood Pressure; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D006977:Hypertension, Renal / Q000201:enzymology* / Q000503:physiopathology; D007684:Kidney Tubules / Q000201:enzymology*; D007686:Kidney Tubules, Distal / Q000201:enzymology; D007687:Kidney Tubules, Proximal / Q000201:enzymology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism* / Q000502:physiology
D017301:Ca(2+) Mg(2+)-ATPase; D000254:Sodium-Potassium-Exchanging ATPase