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Calcium antagonists and the kidney. Implications for renal protection
1Nephrology Section, VA Medical Center, Miami, FL 33125.
Abstract:
During the past decade, attention has been focused on the effects of calcium antagonists on renal function. When administered in vitro to the isolated perfused kidney (IPK), calcium antagonists exhibit consistent actions, permitting characterization of their renal effects. Calcium antagonists do not affect the vasodilated IPK, but do dramatically alter the hemodynamic response of the kidney to vasoconstrictor agents. Our recent studies using the isolated perfused hydronephrotic rat kidney model, which permits direct visualization of afferent and efferent arterioles, demonstrate that the preferential augmentation of glomerular filtration rate (GFR) observed in the IPK is attributable to preferential vasodilation of preglomerular vessels. Although the clinical implications of such observations have not been fully delineated, recent studies indicate that calcium antagonists exert salutary effects on renal function in clinical settings, characterized by impaired renal hemodynamics such as radiocontrast-induced nephrotoxicity and transplant-associated acute renal insufficiency. It is apparent, however, that the salutary effects of calcium antagonists on renal hemodynamics recommend their use in the management of essential hypertension.
Insights
Calcium antagonists improve kidney function by dilating blood vessels, particularly in conditions with impaired renal hemodynamics. These findings support their use in managing hypertension and preventing kidney damage.
Area of Science:
- Nephrology
- Pharmacology
Background:
- Calcium antagonists are increasingly studied for their effects on renal function.
- Their actions can be characterized using the isolated perfused kidney (IPK) model.
Purpose of the Study:
- To investigate the specific renal hemodynamic effects of calcium antagonists.
- To elucidate the mechanisms behind their protective actions in various renal conditions.
Main Methods:
- Utilizing the isolated perfused hydronephrotic rat kidney model for direct arteriolar visualization.
- Administering calcium antagonists in vitro to assess effects on renal hemodynamics and glomerular filtration rate (GFR).
Main Results:
- Calcium antagonists do not affect vasodilated kidneys but alter responses to vasoconstrictors.
- Preferential vasodilation of preglomerular vessels by calcium antagonists augments GFR.
- These agents show beneficial effects in radiocontrast-induced nephrotoxicity and transplant-associated renal insufficiency.
Conclusions:
- Calcium antagonists preferentially dilate preglomerular vessels, enhancing GFR.
- Their salutary effects on renal hemodynamics suggest utility in managing essential hypertension and acute renal insufficiency.
- Further clinical delineation of their renal protective effects is warranted.