Identification of type 1 IP3 receptors in the rat kidney and their modulation by immobilization stress

Inositol 1,4,5-trisphosphate receptor (IP3-receptor) is a calcium channel, transporting calcium from intracellular stores to the cytoplasm. In kidney, IP3-receptors are involved in the signal transduction of various hormones. In our work we studied the effect of immobilization stress on the IP3-rece ptor's protein content in renal cortex and the medulla of normotensive and hypertensive rats. We detected both mRNA and type 1 IP3-receptor protein in medulla, but not in renal cortex. We found that this receptor was approxim ately twice as abundant in normotensive as in genetically hypertensive rat kidney. Immobilization stress decreased the amount of type 1 IP3-receptor i n the renal medulla of normotensive rats approximately five times, while no effect due to single and/or repeated stress was observed in the renal medu lla of spontaneously hypertensive rats. The results indicate that expressio n of type 1 IP3-receptor in renal medulla is modulated by hypertension and immobilization stress. (C) 2000 Elsevier Science B.V. All rights reserved.