EFFECT OF POSTMORTEM DELAY ON DENSITY OF TACHYKININ RECEPTORS IN RAT PERIPHERAL-TISSUES

The effect of post-mortem delay on the affinity and density of tachyki nin NK1 and NK2 receptors was examined in the rat submandibular gland and gastric fundus, respectively, using saturation binding studies wit h the radioligands [I-125]Bolton-Hunter [Sar(9), Met(O-2)(11)]SP and [ I-125][Lys(5), Tyr(I-2)(7), MeLeu(9), Nle(10)]NKA(4-10). For NK1 recep tors, no significant changes were seen in either K-d (control 375 +/- 35 pM, n = 5; 32 h post-mortem 390 +/- 59 pM, n = 5) or B-max (control 96 +/- 16 fmol/mg protein, n = 5; 32 h post-mortem 62 +/- 10 fmol/mg protein, n = 5). For NK2 receptors, no alterations were seen up to 16 h post-mortem. However, significant (p < 0.001) changes were seen at 3 2 h post-mortem (n = 4), where values for K-d were increased (3.0 +/- 0.2 nM) and those for B-max were reduced (42 +/- 5.9 fmol/mg protein), relative to control (K-d = 1.3 +/- 0.2 nM; B-max = 208 +/- 30 fmol/mg protein, n = 5). These changes are probably related to observed histo logical deterioration. This study demonstrates the stability of tachyk inin receptors in these peripheral tissues and indicates the suitabili ty of post-mortem tissue as a valid control in future tachykinin recep tor studies. (C) 1998 Elsevier Science Inc.