Carrier-mediated transport of calcium into the in vitro choroid plexus: inhibitory effects of sodium, potassium, and pharmacological agents.

Update Item Information
Title Carrier-mediated transport of calcium into the in vitro choroid plexus: inhibitory effects of sodium, potassium, and pharmacological agents.
Publication Type dissertation
School or College College of Pharmacy
Department Pharmacology & Toxicology
Author Burton, Scott Allison
Date 1982-12
Description To test the hypothesis that sodium modifies calcium influx into the choroid plexus, the volume of distribution of ('45)Ca in rat choroid plexus was measured after various incubation periods in synthetic CSF solutions in which sodium and potassium concentrations were altered. The initial slope of the curve of ('45)Ca volume of distribution versus time is equal to the rate of calcium entrance into the choroid plexus tissue (I(,Ca)). The results indicate that calcium influx into the rat choroid plexus is carrier mediated with a I(,max) of 0.222 liter/kg wet tissue/min at 37(DEGREES)C and a Km equal to 0.275 mM. Sodium and potassium competitively inhibit calcium influx with Km's of 54.1 and 13.4 mM, respectively. Calcium influx is also correlated with the calculated membrane potential. The ('45)Ca volume of distribution at ten minutes, which is approximately equal to the steady state volume and reflects the amount of calcium in the cell cytoplasm, significantly correlates with choroid plexus water content. Total tissue water decreases as tissue calcium increases indicating the possibility of a negative feedback mechanism for calcium in regulating cell water and/or CSF secretion. Both amiloride (10('-3)M) and ouabain (10('-3)M) significantly (P < 0.05) inhibited calcium influx to 41% and 60% respectively of controls. Verapamil, a voltage-dependent calcium channel blocker, had no effect on calcium influx; this indicates that changes in calcium influx due to alterations in membrane potential caused by ouabain probably can not be attributed to opening or closing of voltage-dependent calcium channels. It is postulated that calcium, sodium and potassium compete for the inward arm of a cation/cation antiport system in the choroid plexus and that amiloride and ouabain influence calcium influx by directly affecting this membrane carrier. While not excluding membrane potential as a factor which affects calcium influx, extracellular sodium and potassium concentration appear to be dominant factors influencing calcium influx into the lateral ventricle rat choroid plexus.
Type Text
Publisher University of Utah
Subject Physiology; Pharmacology
Subject MESH Calcium; Choroid Plexus
Dissertation Institution University of Utah
Dissertation Name PhD
Language eng
Relation is Version of Digital reproduction of "Carrier-mediated transport of calcium into the in vitro choroid plexus: inhibitory effects of sodium, potassium, and pharmacological agents." Spencer S. Eccles Health Sciences Library. Print version of "Carrier-mediated transport of calcium into the in vitro choroid plexus: inhibitory effects of sodium, potassium, and pharmacological agents." available at J. Willard Marriott Library Special Collection. QP 6.5 1982 B87.
Rights Management © Scott Allison Burton.
Format application/pdf
Format Medium application/pdf
Identifier us-etd2,16965
Source Original: University of Utah Spencer S. Eccles Health Sciences Library (no longer available).
Funding/Fellowship NIH grans NS 13988, GM07579, and AM 20935.
ARK ark:/87278/s6p27cq1
Setname ir_etd
ID 192783
Reference URL https://collections.lib.utah.edu/ark:/87278/s6p27cq1
Back to Search Results