Postglomerular vasoconstriction induced by dopamine D(3) receptor activation in anesthetized rats

Area of Science:

• Pharmacology
• Nephrology
• Physiology

Background:

• Dopamine receptors, particularly D(3), play a role in regulating renal function.
• Understanding the specific effects of D(3) receptor activation on renal hemodynamics is crucial for potential therapeutic applications.

Purpose of the Study:

• To investigate the renal hemodynamic effects of dopamine D(3) receptor activation using R(+)-7-hydroxy-dipropylaminotetraline (7-OH-DPAT).

Main Methods:

• Experiments were conducted on thiopental-anesthetized Sprague-Dawley rats.
• Clearance and renal blood flow measurements were performed.
• Micropuncture studies were utilized to assess intrarenal pressures.
• Pharmacological agents, including D(2) and D(3) receptor antagonists, were used.

Main Results:

• 7-OH-DPAT dose-dependently increased glomerular filtration rate (GFR) without altering mean arterial blood pressure (MAP).
• 1.0 microg. kg(-1). min(-1) 7-OH-DPAT increased GFR by 16%, decreased renal blood flow by 20%, and elevated renal vascular resistance by 18%.
• These effects were mediated by D(3) receptor activation, as they were abolished by the D(3) antagonist U-99194A but not by the D(2) antagonist S(-)-sulpiride.
• Micropuncture data indicated elevated stop-flow pressure and reduced efferent arteriolar pressure.

Conclusions:

• Pharmacological activation of dopamine D(3) receptors in anesthetized rats leads to preferential postglomerular vasoconstriction.
• This vasoconstriction results in increased GFR despite reduced renal blood flow.
• The findings highlight a specific role for D(3) receptors in modulating renal vascular resistance.