Abstract
Our goal was to test the hypothesis that A1 receptor blockade induces diuresis/natriuresis with a favorable renal hemodynamic/cardiac profile in aged, lean SHHF/Mcc-facprats, a rodent model of hypertensive dilated cardiomyopathy. Thirteen-month-old SHHF/Mcc-facp rats were pretreated for 72 h before experiments with furosemide (100 mg/kg by gavage 72, 48, and 24 h before experiments) to mimic the clinical setting of chronic diuretic therapy and were given 1% NaCl as drinking water to reduce dehydration/sodium depletion. Animals were instrumented for measurement of systemic and renal hemodynamics, renal excretory function, and cardiac performance, and baseline values were obtained during a 30-min clearance period. Animals then received either vehicle (n = 9), BG9719 [the S-enantiomer of 1,3-dipropyl-8-[2-(5,6-epoxynorbornyl)] xanthine (also called CVT-124)] (highly selective A1 receptor antagonist; 0.1 mg/kg bolus + 10 μg/kg/min; n = 9) or furosemide (loop diuretic; 30 mg/kg; n = 8) and measurements were repeated during four subsequent clearance periods. Both BG9719 and furosemide increased urine volume and absolute and fractional sodium excretion. BG9719 increased renal blood flow and glomerular filtration rate, but did not affect fractional potassium excretion. Furosemide decreased renal blood flow and glomerular filtration rate and increased fractional potassium excretion. Neither drug altered afterload; however, furosemide, but not BG9719, decreased preload (central venous pressure and ventricular end diastolic pressure). Neither drug altered systolic function (+dP/dtmax); however, furosemide, but not BG9719, attenuated diastolic function (decreased −dP/dtmax, increased tau). In the setting of left ventricular dysfunction, chronic salt loading and prior loop diuretic treatment, selective A1 receptor antagonists are effective diuretic/natriuretic agents with a favorable renal hemodynamic/cardiac performance profile.
Footnotes
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This work was supported by a grant from Biogen, Inc., Cambridge, MA.
- Abbreviations:
- GFR
- glomerular filtration rate
- RBF
- renal blood flow
- PE
- polyethylene
- CVP
- central venous pressure
- PEG
- polyethylene glycol
- SBP
- systolic blood pressure
- DBP
- diastolic blood pressure
- MABP
- mean arterial blood pressure
- +dp/dtmax
- maximum rate of rise in intraventricular pressure during ventricular contraction
- −dp/dtmax
- maximum rate of fall in intraventricular pressure during ventricular relaxation
- VPSP
- ventricular peak systolic pressure
- τ
- time constant for ventricular relaxation
- VEDP
- ventricular end diastolic pressure
- VMDP
- ventricular minimal diastolic pressure
- LSD
- least significant difference
- 2-F-ANOVA
- two-factor analysis of variance
- Received June 18, 2001.
- Accepted August 27, 2001.
- The American Society for Pharmacology and Experimental Therapeutics
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