Abnormal renal medullary response to angiotensin II in SHR is corrected by long-term enalapril treatment
| Autor: | Ming-Guo Feng, Stephen A. W. Dukacz, Lufang Yang, Robert M.K.W. Lee, Robert L. Kline |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Male
medicine.medical_specialty Physiology Muscle Relaxation Hemodynamics Angiotensin-Converting Enzyme Inhibitors Blood Pressure Arginine Rats Inbred WKY Renal Artery Enalapril Rats Inbred SHR Physiology (medical) Internal medicine Renin–angiotensin system Laser-Doppler Flowmetry Renal medulla medicine Animals cardiovascular diseases Kidney Medulla Kidney business.industry Angiotensin II Rats Arterioles NG-Nitroarginine Methyl Ester medicine.anatomical_structure Endocrinology Regional Blood Flow Renal blood flow ACE inhibitor cardiovascular system Endothelium Vascular business hormones hormone substitutes and hormone antagonists circulatory and respiratory physiology medicine.drug |
| Zdroj: | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology. 280:R1076-R1084 |
| ISSN: | 1522-1490 0363-6119 |
| Popis: | This study tested the hypotheses that renal medullary blood flow (MBF) in spontaneously hypertensive rats (SHR) has enhanced responsiveness to angiotensin (ANG) II and that long-term treatment with enalapril can correct this. MBF, measured by laser Doppler flowmetry in anesthetized rats, was not altered significantly by ANG II in Wistar-Kyoto (WKY) rats, but was reduced dose dependently (25% at 50 ng · kg−1 · min−1) in SHR. Infusion of N G-nitro-l-arginine methyl ester (l-NAME) into the renal medulla unmasked ANG II sensitivity in WKY rats while l-arginine given into the renal medulla abolished the responses to ANG II in SHR. In 18- to 19-wk-old SHR treated with enalapril (25 mg · kg−1 · day−1 when 4 to 14 wk old), ANG II did not alter MBF significantly, but sensitivity to ANG II was unmasked after l-NAME was infused into the renal medulla. Endothelium-dependent vasodilation (assessed with aortic rings) was significantly greater in treated SHR when compared with that in control SHR. These results indicate that MBF in SHR is sensitive to low-dose ANG II and suggest that this effect may be due to an impaired counterregulatory effect of nitric oxide. Long-term treatment with enalapril improves endothelium-dependent vascular relaxation and decreases the sensitivity of MBF to ANG II. These effects may be causally related to the persistent antihypertensive action of enalapril in SHR. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|