ABSTRACT
PAF represents a new family of glycerophospholipids and possesses multiple biological activities including platelet aggregation. Production of PAF has been demonstrated in a number of different cell types and in response to various stimuli. In this work an attempt is made to study the effect of parathyroid hormone (PTH) on PAF production. In 13 hemodialysis patients with severe secondary hyperparathyroidism, PAF levels in blood as well as intact PTH (iPTH) and total calcium in serum (tCa), before and 10 days after parathyroidectomy (PTHx), were measured. Our results indicate that PAF levels in blood as well as iPTH and tCa were higher before PTHx than after [a) PAF before 1.10 x 10(-4) +/- 9 x 10(-5) gamma/ml and after 2 x 10(-5) +/- 1 x 10(-5) gamma/ml, p < 0.001; b) iPTH before 880 +/- 392.9 pm/ml and after 121.6 +/- 61.9 pm/ml, p < 0.001; c) tCa before 9.96 +/- 0.35 mg/dl and after 8.38 +/- 0.30 mg/dl, p < 0.001]. Using stepwise regression analysis it seems that PAF is dependent on calcium which is dependent mainly on iPTH. Since a) platelet dysfunction is among the factors which are incriminated for bleeding in uremia and b) PAF which induces platelet aggregation acts via specific receptors, we checked the response of platelets in terms of their ability to aggregate in vitro following increasing doses of exogenous PAF in 5 of the above patients in order to investigate whether the high levels of PAF before PTHx may desensitize platelets.(ABSTRACT TRUNCATED AT 250 WORDS)
