Studies on the involvement of calcium and calmodulin in the action of growth-hormone-releasing factor

1984 ◽  
Vol 4 (12) ◽  
pp. 995-1000 ◽  
Author(s):  
Janet E. Merritt ◽  
Pauline R. M. Dobson ◽  
Richard J. H. Wojcikiewicz ◽  
John G. Baird ◽  
Barry L. Brown
Keyword(s):  
Growth Hormone ◽  
Cyclic Amp ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Calcium Mobilization ◽  
Basal Secretion ◽  
Calmodulin Antagonist ◽  
Growth Hormone Releasing Factor ◽  
Gh Secretion

A possible role for Ca 2+ and calmodulin in the action of growth-hormone-releasing factor (GHRF) was investigated. Low extracellular Ca2+ (<100 μM), methoxyverapamil, flunarizine, cinnarizine, and Co2+ decreased both basal and GHRF-stimulated growth-hormone secretion, but did not totally inhibit GHRF-stimulation secretion. A calmodulin antagonist, W7, abolished GHRF-stimulated GH secretion, with no effect on basal secretion. It is suggested that GHRF may act primarily by elevating cellular cyclic AMP, which may then modulate calcium mobilization or flux; the increased intracellular Ca2+ concentrations may then activate calmodulin.

Diurnal administration of human growth hormone-releasing factor does not modify sleep and sleep-related growth hormone secretion in normal young men

1985 ◽  
Vol 110 (2) ◽  
pp. 158-163 ◽  
Author(s):  
Philippe Garry ◽  
Bernard Roussel ◽  
Richard Cohen ◽  
Sylviane Biot-Laporte ◽  
Abdel Elm Charfi ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Young Adult ◽  
Human Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Human Growth ◽  
Adult Males ◽  
Growth Hormone Releasing Factor ◽  
Gh Secretion ◽  
Sleep Parameters

Abstract. hGRF (iv 50 μg) was administered to 6 normal young adult males at 09.00 and 20.00 h on different days. Nocturnal GH secretion was monitored during polygraphic sleep recordings on both control nights and nights following hGRF administration. Sleep-related GH secretion and sleep parameters were not affected by diurnal hGRF administration.

STIMULATION OF GROWTH HORMONE SECRETION IN MONKEYS BY ADRENALIN, PITRESSIN AND ADENOSINE-3′5′-CYCLIC MONOPHOSPHORIC ACID (3′5′-AMP)

1968 ◽  
Vol 59 (3) ◽  
pp. 390-396 ◽  
Author(s):  
J. J. Gagliardino ◽  
J. M. Martin
Keyword(s):  
Growth Hormone ◽  
Cyclic Amp ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Adenyl Cyclase ◽  
Serum Growth Hormone ◽  
Stimulatory Action ◽  
Amp System ◽  
Gh Secretion ◽  
Stimulation Of

ABSTRACT Serum growth hormone (GH) levels were measured by immunoassay in anaesthetized, non-fasted female Rhesus monkeys. Adrenalin and Pitressin® administration significantly stimulated growth hormone secretion. I. v. injection of adenosine-3′5′-cyclic monophosphoric acid (3′5′-AMP) mimicked the stimulatory action of both adrenalin and Pitressin. The stimulation of GH secretion by 3′5′-AMP was blocked by dihydroergotamine. These results suggest that the effect of either adrenalin or Pitressin or both on GH secretion is mediated by the adenyl-cyclase – cyclic AMP system. The additional observation that Pitressin depresses at the same time the release of insulin may indicate that the adenyl-cyclase – cyclic AMP system acts as a common intermediate in the growth hormone-insulin balance.

Secretory bursts of growth hormone secretion in the dog may be initiated by somatostatin withdrawal

1984 ◽  
Vol 62 (2) ◽  
pp. 199-207 ◽  
Author(s):  
John S. Cowan ◽  
Penney Gaul ◽  
Bruce C. Moor ◽  
Jacob Kraicer
Keyword(s):  
Growth Hormone ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Metabolic Clearance ◽  
Time Data ◽  
Basal Secretion ◽  
Gh Secretion ◽  
Plasma Gh ◽  
Secretion Rates

In 28 6-h experiments on 10 conscious resting trained male dogs, plasma growth hormone (GH) was determined at 5-min intervals by radioimmunoassay. For all experiments, the basal GH concentration in plasma was 0.80 ± 0.06 ng mL−1. In each experiment, 1–3 secretory bursts of GH occurred, raising plasma GH 2.4 to 15.3 times basal concentrations (for all 43 bursts, 6.6 ± 0.4 times the basal value). Metabolic clearance rates (MCR) and apparent distribution volumes (V) were determined, using stepwise infusions of canine GH. The MCR (3.99 ± 0.30 mL kg−1 min−1) and V (57.9 ± 5.5 mL kg−1) were used to transform the GH concentration versus time data into GH secretion rates, using a single compartment approach. Basal GH secretion rates for all 28 experiments were 3.12 ± 0.24 ng kg−1 min−1. The secretory bursts yield peak GH secretion rates of 9.4 ± 0.8 times basal secretion and these steep-sloped bursts last 25.1 ± 1.2 min. Six-hour infusions of 0.15 μg kg−1 min−1 of somatostatin (SRIF) abolished all secretory bursts but did not lower basal secretion rates. In five of seven SRIF infusion experiments in which samples were taken after the infusion ceased a secretory burst was seen in the hour following cessation of infusion (in four cases within 10 min). These secretory bursts lasted 23.0 ± 2.9 min and were similar to those seen in control experiments. Infusions of SRIF at 0.05 μg kg−1 min−1 had no effect. These results imply that during basal GH secretion, a surfeit of SRIF impinges on the somatotrophs, as extra SRIF does not further lower basal secretion. However, during secretory bursts, very little SRIF must be present, as exogenous SRIF blocks these bursts. The bursts are similar in duration to overshoots provoked in perifused dispersed rat somatotrophs by removal of an SRIF signal. It seems likely that their cause in vivo is similar. (All values are means ± SEM.)

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