The objective of this study was to determine if the alpha-2 (α2) adrenoceptor agonist oxymetazoline would inhibit Pf in collecting duct nephron segments. The isolated perfused tubule technique was used to determine Pf by measuring net fluid flux in the presence of a lumen-to-bath osmotic gradient and by calculating Pf via standard equations. One set of studies was conducted using CCDs isolated from Sprague-Dawley rat kidneys and another set was conducted in terminal IMCDs isolated from Wistar rat kidneys. Experimental agents were added to the bathing solution, and all experiments were conducted at 37°C. Arginine vasopresein (AVP) at 220pM was used to increase Pf. Oxymetazoline and the α2 antagonist atipamezole were used at 1 μM. The sequence of periods and the results (Pf, μm/sec, mean±se) are shown below. Control AVP AVP+Oxy AVP+Oxy+Ati CCDs (n=7) -16±35 748±92* 295±113† 580±93® IMCPs (n=5) 3±1 140±6* 32±3* 76±3* *, † and ® - significantly different from the previous period (p<.001), (p<.005), and (p<.05), respectively. Oxy - oxymetazoline, Ati - atipamezole. We conclude that oxymetazoline, a partial α2A adrenoceptor agonist, inhibits AVP-stimulated Pf in the rat CCD and IMCD.
|State||Published - 1 Dec 1997|