Effects of diadenosine polyphosphates on glomerular volume

Abstract

1 Diadenosine polyphosphates (P 1 ,P 3 -diadenosine triphosphate, Ap 3 A; P 1 ,P 4 -diadenosine tetraphosphate, Ap 4 A; and P 1 ,P 5 -diadenosine pentaphosphate, Ap 5 A) are vasoactive molecules. The experimental model of isolated rat renal glomeruli was used to investigate their effects on glomerular vasculature. We measured the changes of glomerular inulin space (GIS) as a marker of glomeruli contractility. 2 Ap 4 A and Ap 5 A induced concentration-and time-dependent reduction of GIS whereas Ap 3 A had no effect. The effects of Ap 4 A and Ap 5 A (both at 1 mM) were prevented by a nonselective P2 receptor antagonist, that is, suramin (10 mM) and P2Y receptor antagonist -reactive blue 2 (50 mM). However, the antagonist of P1 receptor, that is, theophylline (1 mM) and A 1 receptor 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 10 mM) did not affect the responses of glomeruli to Ap 4 A or Ap 5 A. 3 Ap 3 A, in contrast to Ap 4 A and Ap 5 A, prevented angiotensin II-induced reduction of GIS in a concentration-and time-dependent manner. This effect was partially prevented by suramin and markedly reduced by reactive blue 2 and the specific antagonist of P2Y 1 receptor -MRS 2179 (10 mM). However, theophylline and the specific antagonist of A 2 receptor -3,7-dimethyl-1-propargylxanthine (DMPX; 10 mM) -did not affect Ap 3 A action. Abbreviations: Ap n As, diadenosine polyphosphates; Ap 3 A, P 1 ,P 3 -diadenosine triphosphate; Ap 4 A, P 1 ,P 4 -diadenosine tetraphosphate; Ap 5 A, P 1 ,P 5 -diadenosine pentaphosphate; DMPX, 3,7-dimethyl-1-propargylxanthine; DPCPX, 8-cyclopentyl-1,3-dipropylxanthine; GIS, glomerular inulin space; MRS 2179, 2 0 -deoxy-N 6 -methyl adenosine 3 0 5 0 -diphosphate diammonium salt; PBS, phosphate-buffered saline

Diadenosine pentaphosphate modulates glomerular arteriolar tone and glomerular filtration rate

“…Ap 3 A increased it, indicating a modulatory role of Ap n A on the GFR (Szczepanska‐Konkel et al . ). Another dinucleoside polyphosphate, namely Up 4 A, also elicits afferent arteriolar vasoconstriction with no effect on efferent arterioles (Jankowski et al .…”

Purinergic signalling in the kidney in health and disease

“…Diadenosine pentaphosphate (Ap 5 A) and diadenosine hexaphosphate appear to play a regulatory role in mesangial cell proliferation [129]. Ap 4 A and Ap 5 A decrease, while diadenosine triphosphate appears to increase glomerular filtration rate [359].…”

Tumor necrosis factor-alpha-induced reduction of glomerular filtration rate in rats with fulminant hepatic failure

“…GAPDH was used for a house-keeping gene control. 24 Isolation of Rat Glomeruli Animals were decapitated under ether anesthesia and kidneys were collected. The glomeruli were isolated by a gradual sieving technique.…”

“…Tubular contamination was less than 5% as assessed under the light microscope. The entire procedure was carried out in an ice bath within 1 h. 23,24 Determination of Glomerular Inulin Space About 4000 glomeruli were resuspended in 400 ml ice-cold Ca 2 þ -free buffer (containing 1% bovine serum albumin). They were incubated with FITC-inulin (100 mg, Sigma) at 37 1C in shaking water bath for 30 min, then equally divided into two tubes.…”

“…Fluorescence intensity (FI) of glomeruli was measured by a spectrofluorometer. Glomerular inulin space (GIS) of single glomerulus was calculated as follows: 23,24 GIS ðnl=glomerulusÞ ¼ FI À pellet ðmg=mlÞ FI À supernatant ðmg=mlÞ Â 1 number of glomeruli in pellet Measurements of Intracellular [Ca 2 þ ]i in Glomeruli Glomeruli were isolated according to the method described above. Two thousand glomeruli were resuspended in 200 ml Hank's saline solution and incubated with Fura-2/AM (10 mM) at 37 1C in dark shaking water bath for 45 min.…”