nitrophenols and Hypertension--Renal

Efonidipine, a calcium antagonist, has been reported to dilate not only afferent but also efferent arterioles, thereby reducing glomerular hydrostatic pressure. We investigated the effect of chronic treatment with efonidipine or lisinopril on the afferent and efferent arteriolar diameters by the vascular cast technique. Four-week-old spontaneously hypertensive rats (SHR) were divided into three groups: untreated, efonidipine (25 mg/kg/day)-treated, and lisinopril (3 mg/kg/day)-treated. At 22 weeks of age, the renal vasculatures were fixed at the maximally dilated condition. The morphometrical measurements showed that the treatments with efonidipine and lisinopril caused structural alteration of the vasculature, resulting in significantly greater efferent arteriolar diameters than in untreated SHR. In addition, lisinopril-treated rats had wider afferent lumina. The renoprotective effect of efonidipine and lisinopril might be partly due to the structurally larger efferent arteriolar lumen.

Topics: Animals; Arterioles; Blood Pressure; Body Weight; Calcium Channel Blockers; Corrosion Casting; Dihydropyridines; Hypertension, Renal; Kidney Glomerulus; Male; Nitrophenols; Organophosphorus Compounds; Rats; Rats, Inbred SHR; Renal Circulation

1. We investigated the effects of short- and long-term administration of efonidipine hydrochloride (NZ-105), 1,4-dihydropyridine derivative, in conscious spontaneously hypertensive rats (SHR). 2. Oral administration of NZ-105 for 12 weeks caused diuretic and natriuretic effects, which were not attenuated during the experimental period. 3. In the short-term experiment for investigating the mechanism of the diuretic effect, intravenous injection of NZ-105 (0.03 mg/kg of body weight) significantly increased the urine volume (UV), renal plasma flow (RPF) and glomerular filtration rate (GFR). The increment rate of UV and RPF was 105.4 +/- 17.8% and 111.7 +/- 72.8%, respectively, which were larger than the increment rate of GFR (38.5 +/- 14.0%). 4. The diuretic or natriuretic effect of NZ-105 was suggested to be due to both the inhibition of sodium reabsorption and, at least in part, the increase of GFR.

Topics: Animals; Calcium Channel Blockers; Dihydropyridines; Diuretics; Drug Administration Schedule; Hypertension, Renal; Kidney; Male; Nitrophenols; Organophosphorus Compounds; Potassium; Rats; Rats, Inbred SHR; Renal Circulation; Sodium

Hypertension induces hypertrophy and increased turnover of aortic smooth muscle cells along with an accumulation of connective tissue in the aortic wall. We identified the lysosomes in normal and hypertensive aortic muscle cells by light and electron microscopy, utilizing cytochemical staining for acid phosphatase activity. Lysosomes were found to be more numerous in hypertensive vessels. Biochemical assays of two specific lysosomal enzymes revealed a doubling of acid phosphatase and a more than threefold increase in beta-N-acetyl-glucosaminidase activities in hypertensive aortas.

Topics: Acid Phosphatase; Animals; Aorta; Aorta, Thoracic; DNA; Glycerophosphates; Hexosaminidases; Histocytochemistry; Hypertension, Renal; Lysosomes; Male; Microscopy; Microscopy, Electron; Muscle, Smooth; Nitrophenols; Rats