Related Experiment Videos
Effect of carvedilol on renal hemodynamics and renal excretory function in spontaneously hypertensive rats
M Gellai1, R DeWolf, R R Ruffolo
1Department of Pharmacology, SmithKline Beecham Pharmaceuticals, King of Prussia, Pa.
Insights
Carvedilol effectively lowers blood pressure in hypertensive rats without negatively impacting kidney function or sodium excretion. This antihypertensive agent demonstrates a beneficial "renal sparing" effect, unlike labetalol.
Area of Science:
- Pharmacology
- Nephrology
- Cardiovascular Research
Background:
- Hypertension management requires careful consideration of renal function.
- Novel antihypertensive agents need thorough evaluation for systemic and renal effects.
- Labetalol's impact on renal hemodynamics serves as a comparative benchmark.
Purpose of the Study:
- To investigate the effects of carvedilol on renal hemodynamics and excretory function in spontaneously hypertensive rats.
- To compare carvedilol's renal effects with those of labetalol.
- To determine if carvedilol preserves renal autoregulation and electrolyte balance during blood pressure reduction.
Main Methods:
- Conscious, spontaneously hypertensive rats received sustained intravenous infusions of carvedilol or labetalol.
- Key renal hemodynamic parameters (glomerular filtration rate, renal blood flow, filtration fraction) were monitored.
- Urine flow, osmolality, and electrolyte (sodium, potassium) excretion were measured.
Main Results:
- Both carvedilol and labetalol significantly reduced blood pressure equally.
- Carvedilol did not alter glomerular filtration rate, renal blood flow, or filtration fraction.
- Labetalol decreased glomerular filtration rate and filtration fraction, while carvedilol maintained stable sodium and potassium excretion.
Conclusions:
- Carvedilol exhibits a "renal sparing" effect, lowering blood pressure without compromising renal autoregulatory integrity.
- Unlike labetalol, carvedilol does not impair urinary sodium excretion in hypertensive rats.
- Carvedilol represents a potentially advantageous antihypertensive therapy for patients where renal function is a concern.
Abstract:
The effects of the novel antihypertensive agent, carvedilol, on renal hemodynamics and excretory function have been investigated and compared with the effects of labetalol in conscious, spontaneously hypertensive rats. Sustained intravenous infusion of carvedilol or labetalol at a rate of 10 micrograms/kg/min resulted in a significant decrease in blood pressure which was equivalent in magnitude for both drugs. Carvedilol had no effect on renal hemodynamic parameters; glomerular filtration rate, renal blood flow, and filtration fraction were unchanged. In contrast, labetalol decreased the glomerular filtration rate by 13% (p less than 0.01) and the filtration fraction was reduced from 28 to 24%. Inasmuch as renal blood flow was unchanged and perfusion pressure was reduced, both compounds decreased renal vascular resistance. Urine flow decreased and osmolality increased with both carvedilol and labetalol. However, excretion of electrolytes was affected differently with the two compounds. While sodium and potassium excretion were significantly decreased with labetalol, sodium and potassium excretion remained stable during carvedilol infusion, which represents an important beneficial effect for a potent systemic vasodilator. We conclude, therefore, that carvedilol does not compromise the renal autoregulatory integrity in hypertensive rats, and that the antihypertensive activity of the compound is associated with an apparent 'renal sparing' effect, in that the decrease in blood pressure does not compromise the urinary excretion of sodium.