# 45CA2+ FLUX IN NORMAL AND NEOPLASTIC PITUITARY CELLS

> **NIH NIH R01** · UNIVERSITY OF VIRGINIA · 1988 · $140,120

## Abstract

Dopaminergic (DA) treatment of hyperprolactinemia caused by prolactin (Prl)
secreting pituitary neoplasms is a striking example of successful medical
management of human neoplasia.  The treatment typically shrinks the tumor,
reduces Prl levels and restores fertility.  The cytoplasmic free calcium
level has a critical role in regulating Prl secretion and that of other
hormones.  However, there is yet much to learn about how physiological
agents like DA may regulate the cytoplasmic calcium concentration to
control hormone secretion.  We aim to study calcium flux in normal and
neoplastic pituitary cells under the direct influence of THREE agents with
IMPORTANT effects on hormone secretion:  DA, growth hormone releasing
factor (GRF), and SOMATOSTATIN (SRIF).  To satisfy these aims and expand
our knowledge about the regulation of hormone secretion under normal and
pathological conditions three important parameters of 45Ca2+ flux will be
comprehensively analyzed.  To study 1) 45Ca2+ uptake and 2) net flux at
isotopic equilibrium, normal or neoplastic rat pituitary cells are
dispersed into a single cell suspension and incubated in 45Ca2+ followed by
rapid vacuum filtration and washing.  Calcium flux as a function of 45Ca2+
specific activity is then calculated from the radioactivity within the
cells trapped on each filter.  The third parameter, 45Ca2+ efflux, is
directly measured as the fractional loss from prelabeled cells using a
perifusion apparatus.

Regulation of calcium flux has been speculated to be the basis for DA
control of Prl secretion yet this vital question has not been critically
evaluated.  We know that GRF is dependent in some manner on calcium to
stimulate growth hormone secretion, but although important, specific
details about this dependency are unknown.  SRIF IS A NATURALLY OCCURRING
PEPTIDE WHICH INHIBITS THE SECRETION OF GH, AS WELL AS MANY OTHER
BIOLOGICALLY ACTIVE HORMONES.  MODULATION OF CALCIUM FLUX BY SRIF HAS BEEN
TENTATIVELY INFERRED AS ONE MECHANISM CONTRIBUTING TO ITS ACTION, BUT
RIGOROUS INVESTIGATION IS LACKING.

The preliminary studies are promising; the experiments are rationally
organized; and the resources and environment suitable for the efficient
execution of this three year program.

## Key facts

- **NIH application ID:** 3176319
- **Project number:** 5R01CA038228-03
- **Recipient organization:** UNIVERSITY OF VIRGINIA
- **SAM.gov UEI:** JJG6HU8PA4S5
- **Principal Investigator:** IVAN S LOGIN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 1988
- **Award amount:** $140,120
- **Award type:** 5
- **Project period:** 1985-12-01 → 1989-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/3176319

## Citation

> US National Institutes of Health, RePORTER application 3176319, 45CA2+ FLUX IN NORMAL AND NEOPLASTIC PITUITARY CELLS (5R01CA038228-03). Retrieved via MORVS 2026-10-25 from https://api.morvs.ai/grant/nih/3176319. Licensed CC0.

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