PMID- 9681184
OWN - NLM
STAT- MEDLINE
DCOM- 19980824
LR  - 20190921
IS  - 0143-4160 (Print)
IS  - 0143-4160 (Linking)
VI  - 23
IP  - 4
DP  - 1998 Apr
TI  - Growth hormone-releasing factor mobilizes cytosolic free calcium through 
      different mechanisms in two somatotrope subpopulations from porcine pituitary.
PG  - 207-17
AB  - Porcine somatotropes can be separated by Percoll density gradient centrifugation 
      into low (LD) and high density (HD) subpopulations that differ ultrastructurally 
      and functionally. Here, we report the effects of growth hormone-releasing factor 
      (GRF) on the cytosolic free calcium concentration ([Ca2+]i) of single LD and HD 
      somatotropes. Resting [Ca2+]i in LD somatotropes was 2-fold higher than in HD 
      cells. GRF induced [Ca2+]i increases in a similar percentage of somatotropes from 
      both subsets. However, amplitude and kinetics of the responses were markedly 
      different. In all responsive LD somatotropes, GRF evoked a rapid initial peak 
      followed by a sustained plateau (plateau-type response). Blockade of 
      extracellular Ca2+ entry by 3 mM EDTA, 2 mM CoCl2, or 100 microM verapamil 
      completely abolished the plateau phase without affecting the initial Ca2+ spike. 
      Conversely, only the plateau phase was preserved in thapsigargin (TG)-treated LD 
      cells. The vast majority of GRF-responsive HD somatotropes exhibited a transient 
      [Ca2+]i peak that returned gradually to baseline (transient-type response). This 
      response was completely blocked by removal of extracellular Ca2+, whereas TG 
      treatment had no effect. Taken together, our results indicate that the response 
      of LD somatotropes to GRF depends on mobilization of Ca2+ of both extra- and 
      intracellular origin, whereas that of HD somatotropes seems to be exclusively 
      dependent on extracellular Ca2+ entry through L-type voltage sensitive Ca2+ 
      channels (VSCC). These findings are the first to demonstrate a differential 
      effect of GRF on Ca2+ mobilization in two somatotrope subpopulations, and suggest 
      the existence of differences in the GRF receptor(s) expressed in each 
      subpopulation and/or in the intracellular signalling pathways activated upon GRF 
      binding.
FAU - Ramirez, J L
AU  - Ramirez JL
AD  - Department of Cell Biology, Faculty of Sciences, University of Cordoba, Spain.
FAU - Torronteras, R
AU  - Torronteras R
FAU - Malagon, M M
AU  - Malagon MM
FAU - Castano, J P
AU  - Castano JP
FAU - Garcia-Navarro, S
AU  - Garcia-Navarro S
FAU - Gonzalez de Aguilar, J L
AU  - Gonzalez de Aguilar JL
FAU - Martinez-Fuentes, A J
AU  - Martinez-Fuentes AJ
FAU - Gracia-Navarro, F
AU  - Gracia-Navarro F
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - Cell Calcium
JT  - Cell calcium
JID - 8006226
RN  - 0 (Calcium Channel Blockers)
RN  - 0 (Chelating Agents)
RN  - 0 (Receptors, Neuropeptide)
RN  - 0 (Receptors, Pituitary Hormone-Regulating Hormone)
RN  - 3G0H8C9362 (Cobalt)
RN  - 67526-95-8 (Thapsigargin)
RN  - 9002-72-6 (Growth Hormone)
RN  - 9034-39-3 (Growth Hormone-Releasing Hormone)
RN  - 9G34HU7RV0 (Edetic Acid)
RN  - CJ0O37KU29 (Verapamil)
RN  - EVS87XF13W (cobaltous chloride)
RN  - F8L0ODC9D7 (somatotropin releasing hormone receptor)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Calcium/*metabolism
MH  - Calcium Channel Blockers/pharmacology
MH  - Cell Compartmentation
MH  - Cell Separation
MH  - Centrifugation, Density Gradient
MH  - Chelating Agents/pharmacology
MH  - Cobalt/pharmacology
MH  - Cytosol/metabolism
MH  - Edetic Acid/pharmacology
MH  - Extracellular Space/metabolism
MH  - Female
MH  - Growth Hormone/metabolism
MH  - Growth Hormone-Releasing Hormone/*pharmacology
MH  - Ion Transport/drug effects
MH  - Pituitary Gland, Anterior/cytology/*drug effects/metabolism
MH  - Receptors, Neuropeptide/classification/drug effects
MH  - Receptors, Pituitary Hormone-Regulating Hormone/classification/drug effects
MH  - Signal Transduction
MH  - Swine
MH  - Thapsigargin/pharmacology
MH  - Verapamil/pharmacology
EDAT- 1998/07/29 00:00
MHDA- 1998/07/29 00:01
CRDT- 1998/07/29 00:00
PHST- 1998/07/29 00:00 [pubmed]
PHST- 1998/07/29 00:01 [medline]
PHST- 1998/07/29 00:00 [entrez]
AID - S0143-4160(98)90119-1 [pii]
AID - 10.1016/s0143-4160(98)90119-1 [doi]
PST - ppublish
SO  - Cell Calcium. 1998 Apr;23(4):207-17. doi: 10.1016/s0143-4160(98)90119-1.