Early endothelial dysfunction following renal mass reduction in rats

Area of Science:

• Cardiovascular Physiology
• Renal Physiology
• Endothelial Function

Background:

• Endothelial dysfunction is known in hypertensive rats with renal mass reduction (RMR) and high sodium intake.
• The specific impact of renal failure on endothelium-dependent vasodilation, independent of hypertension and sodium, remains unclear.

Purpose of the Study:

• To investigate the early effects of renal mass reduction (RMR) on endothelium-dependent vasodilation in rats.
• To determine the role of nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor (EDHF) in mediating these changes.

Main Methods:

• Mesenteric arteries from RMR and sham-operated (SN) rats were studied for responses to acetylcholine.
• The involvement of nitric oxide (L-NAME), prostacyclin (indomethacin), and EDHF (charybdotoxin/apamin) was assessed using specific inhibitors.
• Urinary and perfusate levels of 6-keto prostaglandin F1alpha were measured.

Main Results:

• Acetylcholine-induced relaxation was impaired in RMR rats compared to SN rats.
• Nitric oxide inhibition (L-NAME) further reduced relaxation in SN but not RMR rats.
• Prostacyclin inhibition (indomethacin) impaired relaxation in RMR rats but not SN rats, with elevated prostaglandin levels observed in RMR rats.

Conclusions:

• Endothelial dysfunction develops early after RMR, even with minimal hypertension and normal sodium intake.
• This dysfunction may stem from decreased nitric oxide availability.
• Increased prostacyclin production appears to partially compensate for the impaired vasodilation.