It has been suggested that excess parathyroid hormone (PTH) in chronic renal failure (CRF) or chronic administration of PTH to normal rats caused derangements in norepinephrine and phospholipid metabolism of brain synaptosomes, because of an increase in their resting levels of cytosolic calcium which may induce a decrease in synaptosomal content of ATP. In the study presented here, the resting levels of cytosolic calcium in brain synaptosomes were measured in six groups of rats including: (1) normal rats; (2) rats with CRF of 21-days duration; (3) normocalcemic parathyroidectomized rats with CRF of 21-days duration; (4) rats with CRF of 21-days duration treated with verapamil from day 1 of CRF; (5) normal rats treated with verapamil for 21 days; and (6) normal rats treated with PTH for 21 days. Resting levels of cytosolic calcium of brain synaptosomes of CRF rats (437 +/- 18.0 nM) and normal rats treated with PTH (428 +/- 5.6 nM) were significantly (P < 0.01) higher than those of normal rats (345 +/- 9.0 nM), normal rats treated with verapamil (354 +/- 8.7 nM), CRF rats treated with verapamil (361 +/- 12.9 nM), or CRF-parathyroidectomized rats (363 +/- 8.2 nM). There were no significant differences between the values of the last three groups of rats. The ATP content of brain synaptosomes of CRF rats (2.95 +/- 0.23 nmol/mg of protein) and normal rats treated with PTH (3.06 +/- 0.13 nmol/mg of protein) were significantly (P < 0.01) lower than that in normal rats (4.49 +/- 0.30 nmol/mg of protein), normal rats treated with verapamil (4.60 +/- 0.30 nmol/mg of protein), CRF rats treated with verapamil (4.05 +/- 0.25 nmol/mg of protein), or CRF-parathyroidectomized rats (4.03 +/- 0.22 nmol/mg of protein). There were no significant differences between the values of the last three groups of animals. The data demonstrate that chronic excess of PTH in the presence or absence of CRF is associated with significant elevations in the resting levels of cytosolic calcium of brain synaptosomes and significant reduction of their ATP content.
|Titolo:||CHRONIC PARATHYROID-HORMONE EXCESS INVIVO INCREASES RESTING LEVELS OF CYTOSOLIC CALCIUM IN BRAIN SYNAPTOSOMES - STUDIES IN THE PRESENCE AND ABSENCE OF CHRONIC-RENAL-FAILURE|
|Data di pubblicazione:||1991|
|Appare nelle tipologie:||1.1 Articolo in rivista|