Biomaterial Database

Superficial and juxtamedullary nephron function during converting enzyme inhibition. 1986

A Göransson, and M Sjöquist, and H R Ulfendahl

The influence of the renin-angiotensin system on whole-kidney and regional single-nephron function was studied in anesthetized Munich-Wistar rats by use of a converting enzyme inhibitor (CEI), captopril (3 mg . h-1 . kg-1 body wt-1). Single-nephron glomerular filtration rate (SNGFR) was measured in superficial (S) and juxtamedullary (JM) nephrons by a micropuncture technique that blocked tubuloglomerular feedback (TGF) activity. Hydrostatic free-flow pressure (FFP) measurements were conducted in S proximal tubules, in JM loops of Henle, and in papillary vasa recta. Glomerular filtration rate (GFR) and urinary electrolyte excretion were measured in the contralateral kidney. In the control situation SNGFR of S nephrons was 35.4 +/- 2.24 nl . min-1 . g kidney wt-1 and of JM nephrons was 75.0 +/- 9.41 nl . min-1 . g-1 kidney wt-1. Thus it was more than twice as high in JM as in S nephrons when the TGF activity was blocked. In this situation administration of CEI had no additional effect on either S or JM nephrons. However, administration of CEI resulted in a significant increase in whole-kidney GFR by 25% (P less than 0.05) and in urine flow rate by 60% (P less than 0.001) under free-flow conditions. Further, intratubular FFP increased significantly in JM nephrons by an average of 2.9 +/- 0.52 mmHg (P less than 0.001), indicating an increase in tubular urine flow in JM nephrons, whereas S nephrons were unaffected. These results suggest an active preglomerular vasoconstriction in JM nephrons under normal free-flow conditions. This seems to be mediated by TGF and modulated by angiotensin II.

UI	MeSH Term	Description	Entries
D007687	Kidney Tubules, Proximal	The renal tubule portion that extends from the BOWMAN CAPSULE in the KIDNEY CORTEX into the KIDNEY MEDULLA. The proximal tubule consists of a convoluted proximal segment in the cortex, and a distal straight segment descending into the medulla where it forms the U-shaped LOOP OF HENLE.	Proximal Kidney Tubule,Proximal Renal Tubule,Kidney Tubule, Proximal,Proximal Kidney Tubules,Proximal Renal Tubules,Renal Tubule, Proximal,Renal Tubules, Proximal,Tubule, Proximal Kidney,Tubule, Proximal Renal,Tubules, Proximal Kidney,Tubules, Proximal Renal
D008138	Loop of Henle	The U-shaped portion of the renal tubule in the KIDNEY MEDULLA, consisting of a descending limb and an ascending limb. It is situated between the PROXIMAL KIDNEY TUBULE and the DISTAL KIDNEY TUBULE.	Ascending Limb of Loop of Henle,Descending Limb of Loop of Henle,Henle Loop
D008297	Male		Males
D009399	Nephrons	The functional units of the kidney, consisting of the glomerulus and the attached tubule.	Nephron
D011312	Pressure	A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Pressures
D012084	Renin-Angiotensin System	A BLOOD PRESSURE regulating system of interacting components that include RENIN; ANGIOTENSINOGEN; ANGIOTENSIN CONVERTING ENZYME; ANGIOTENSIN I; ANGIOTENSIN II; and angiotensinase. Renin, an enzyme produced in the kidney, acts on angiotensinogen, an alpha-2 globulin produced by the liver, forming ANGIOTENSIN I. Angiotensin-converting enzyme, contained in the lung, acts on angiotensin I in the plasma converting it to ANGIOTENSIN II, an extremely powerful vasoconstrictor. Angiotensin II causes contraction of the arteriolar and renal VASCULAR SMOOTH MUSCLE, leading to retention of salt and water in the KIDNEY and increased arterial blood pressure. In addition, angiotensin II stimulates the release of ALDOSTERONE from the ADRENAL CORTEX, which in turn also increases salt and water retention in the kidney. Angiotensin-converting enzyme also breaks down BRADYKININ, a powerful vasodilator and component of the KALLIKREIN-KININ SYSTEM.	Renin-Angiotensin-Aldosterone System,Renin Angiotensin Aldosterone System,Renin Angiotensin System,System, Renin-Angiotensin,System, Renin-Angiotensin-Aldosterone
D002216	Captopril	A potent and specific inhibitor of PEPTIDYL-DIPEPTIDASE A. It blocks the conversion of ANGIOTENSIN I to ANGIOTENSIN II, a vasoconstrictor and important regulator of arterial blood pressure. Captopril acts to suppress the RENIN-ANGIOTENSIN SYSTEM and inhibits pressure responses to exogenous angiotensin.	(S)-1-(3-Mercapto-2-methyl-1-oxopropyl)-L-proline,Capoten,Lopirin,SQ-14,225,SQ-14,534,SQ-14225,SQ-14534,SQ 14,225,SQ 14,534,SQ 14225,SQ 14534,SQ14,225,SQ14,534,SQ14225,SQ14534
D004573	Electrolytes	Substances that dissociate into two or more ions, to some extent, in water. Solutions of electrolytes thus conduct an electric current and can be decomposed by it (ELECTROLYSIS). (Grant & Hackh's Chemical Dictionary, 5th ed)	Electrolyte
D005919	Glomerular Filtration Rate	The volume of water filtered out of plasma through glomerular capillary walls into Bowman's capsules per unit of time. It is considered to be equivalent to INULIN clearance.	Filtration Rate, Glomerular,Filtration Rates, Glomerular,Glomerular Filtration Rates,Rate, Glomerular Filtration,Rates, Glomerular Filtration
D000806	Angiotensin-Converting Enzyme Inhibitors	A class of drugs whose main indications are the treatment of hypertension and heart failure. They exert their hemodynamic effect mainly by inhibiting the renin-angiotensin system. They also modulate sympathetic nervous system activity and increase prostaglandin synthesis. They cause mainly vasodilation and mild natriuresis without affecting heart rate and contractility.	ACE Inhibitor,ACE Inhibitors,Angiotensin Converting Enzyme Inhibitor,Angiotensin I-Converting Enzyme Inhibitor,Angiotensin-Converting Enzyme Inhibitor,Kininase II Inhibitor,Kininase II Inhibitors,Angiotensin I-Converting Enzyme Inhibitors,Angiotensin-Converting Enzyme Antagonists,Antagonists, Angiotensin-Converting Enzyme,Antagonists, Kininase II,Inhibitors, ACE,Inhibitors, Angiotensin-Converting Enzyme,Inhibitors, Kininase II,Kininase II Antagonists,Angiotensin Converting Enzyme Antagonists,Angiotensin Converting Enzyme Inhibitors,Angiotensin I Converting Enzyme Inhibitor,Angiotensin I Converting Enzyme Inhibitors,Antagonists, Angiotensin Converting Enzyme,Enzyme Antagonists, Angiotensin-Converting,Enzyme Inhibitor, Angiotensin-Converting,Enzyme Inhibitors, Angiotensin-Converting,II Inhibitor, Kininase,Inhibitor, ACE,Inhibitor, Angiotensin-Converting Enzyme,Inhibitor, Kininase II,Inhibitors, Angiotensin Converting Enzyme