Hyperparathyroidism, platelet intracellular free calcium and hypertension in chronic renal failure

Abstract

To investigate possible relationships between hyperparathyroidism, alterations in intracellular free calcium concentration ([Ca2+]i) and hypertension in chronic renal failure, serum concentrations of intact parathyroid hormone (PTH) were measured by two-site immunometric assay, and platelet ([Ca2+]i) was assessed using the fluorescent indicator fura-2. Thirty-six patients with chronic renal failure were studied, 10 with normal serum PTH concentrations (mean 8.0 +/- 0.6 pmol/liter), 17 with elevated serum PTH (35.0 +/- 7.2 pmol/liter) and 9 patients with elevated PTH (36.2 +/- 5.9 pmol/liter) who were receiving nifedipine. Platelet [Ca2+]i was increased in patients with elevated PTH, compared with those in whom PTH was normal (138 +/- 16 vs. 83 +/- 7 nmol/liter, P < 0.01). A linear relation was observed between serum PTH and platelet [Ca2+]i in these patients (r = 0.818, P < 0.001). In contrast, platelet [Ca2+]i was not elevated (84 +/- 9 nmol/liter) in the patients with elevated PTH who were receiving nifedipine. A linear relation was also present between both serum PTH (r = 0.616, P < 0.001) and platelet [Ca2+]i (r = 0.576, P < 0.005) and mean blood pressure. Nine patients with hyperparathyroidism were restudied after treatment with the vitamin D analogue alfacalcidol. This resulted in significant decreases in serum PTH (P < 0.01), platelet [Ca2+]i (P < 0.02), and mean blood pressure (P < 0.05). These studies indicate that [Ca2+]i may be increased early in renal failure, and that this increase occurs in association with both hyperparathyroidism and hypertension. Furthermore, treatment of hyperparathyroidism with alfacalcidol may result in reductions in both [Ca2+]i and blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Determinants of mean arterial pressure and pulse pressure in chronic haemodialysis patients

“…In a recent study using ambulatory blood pressure monitoring, the PTH level was the major determinant of blood pressure. 28 Moreover, recent observations linking the correction of hyperparathyroidism by either vitamin D administration 29 or parathyroidectomy 30 in chronic dialysis patients, resulting in a lower blood pressure, have supported this hypothesis. In our study, we found a correlation between PTH levels and predialysis MAP, but not PP.…”

Cardiotonic Steroids and Cardiac Fibrosis

“…PTH excess in uremic patients has also been shown to increase cytosolic calcium levels that were correlated with the plasma PTH concentrations. These were also shown to be corrected with parathyroidectomy (PTX) (Raine, Bedford et al 1993). Even though increased calcium entry has been thought to be the most important step in sustaining high intra myocyte calcium concentrations reductions in the NA/K ATPase and Na/H exchange rates suggesting impaired calcium extrusion may contribute to altered cellular calcium homeostasis (Smogorzewski 1995).…”

Pathogenesis and treatment of hypertension in haemodialysis patients with chronic kidney disease

“…The evidence based on a retrospective study in CKD patients demonstrating that systolic and diastolic blood pressure were significantly increased in subjects with increased plasma concentration of parathyroid hormone (PTH) [26]. Furthermore, a possible mechanism was suggested by the findings of increased platelet cytosolic calcium in the group with increased PTH plasma concentration.…”