PMID- 8973577
OWN - NLM
STAT- MEDLINE
DCOM- 19970127
LR  - 20190501
IS  - 0264-6021 (Print)
IS  - 1470-8728 (Electronic)
IS  - 0264-6021 (Linking)
VI  - 320 ( Pt 2)
IP  - Pt 2
DP  - 1996 Dec 1
TI  - Evidence for a Ca2+ pool associated with secretory granules in rat submandibular 
      acinar cells.
PG  - 627-34
AB  - Intracellular Ca2+ stores in rat submandibular acinar cells were characterized 
      using the Ca(2+)-sensitive fluorescent indicator fura 2 and the radiotracer 
      45Ca2+. Acetylcholine induced a rapid Ca2+ release from a store sensitive to 
      inositol 1,4,5-trisphosphate (IP3) and to thapsigargin (TG). After this store was 
      presumably depleted, ionomycin caused a further increase in cytosolic free Ca2+ 
      concentration ([Ca2+]i), suggesting the presence of an IP3-insensitive Ca2+ 
      release from a store that is more extensive and heterogeneous than the 
      IP3-sensitive one and includes a small mitochondrial component. After both of 
      these stores had been discharged, exposure to monensin caused an additional 
      release of Ca2+ from a third store. This store appears to be associated with 
      secretory granules, since Ca2+ release was significantly reduced when 
      degranulation was induced by isoprenaline. This third store appears to be 
      insensitive to IP3, discharges Ca2+ when the pH gradient across the limiting 
      membrane is collapsed with monensin and only in the presence of both ionomycin 
      and monensin. Ca2+ release from this store is not by Na+/Ca2+ exchange, since 
      simply altering [Na+]i did not cause significant Ca2+ release. In permeabilized 
      cells, IP3 and TG released approx. 35% of 45Ca2+, and ionomycin released an 
      additional 57%, whereas monensin only caused a small additional release, 
      suggesting that only IP3- and ionomycin-sensitive stores are loaded with 45Ca2+ 
      under these conditions. The absence of significant isotope uptake into the 
      ionomycin+monensin-sensitive store may result from a low rate of tracer 
      accumulation or from the lack of Ca2+ pumps in the store. The pattern of response 
      was similar in the presence and absence of mitochondrial inhibitors, indicating 
      that the store is not located in mitochondria. In summary, these results suggest 
      that a substantial IP3-insensitive Ca2+ store is present in secretory granules in 
      rat submandibular acinar cells.
FAU - Martinez, J R
AU  - Martinez JR
AD  - Department of Pediatrics, University of Texas Health Science Center at San 
      Antonio 78284, USA.
FAU - Willis, S
AU  - Willis S
FAU - Puente, S
AU  - Puente S
FAU - Wells, J
AU  - Wells J
FAU - Helmke, R
AU  - Helmke R
FAU - Zhang, G H
AU  - Zhang GH
LA  - eng
GR  - DE09270/DE/NIDCR NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - Biochem J
JT  - The Biochemical journal
JID - 2984726R
RN  - 526U7A2651 (Egtazic Acid)
RN  - 56092-81-0 (Ionomycin)
RN  - 67526-95-8 (Thapsigargin)
RN  - 85166-31-0 (Inositol 1,4,5-Trisphosphate)
RN  - 906O0YJ6ZP (Monensin)
RN  - 9NEZ333N27 (Sodium)
RN  - L628TT009W (Isoproterenol)
RN  - N9YNS0M02X (Acetylcholine)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Acetylcholine/pharmacology
MH  - Animals
MH  - Calcium/*metabolism
MH  - Cell Membrane Permeability
MH  - Cytoplasmic Granules/drug effects/*metabolism
MH  - Egtazic Acid/pharmacology
MH  - In Vitro Techniques
MH  - Inositol 1,4,5-Trisphosphate/pharmacology
MH  - Ionomycin/pharmacology
MH  - Isoproterenol/pharmacology
MH  - Kinetics
MH  - Male
MH  - Monensin/pharmacology
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Sodium/pharmacology
MH  - Submandibular Gland/cytology/drug effects/*metabolism
MH  - Thapsigargin/pharmacology
MH  - Time Factors
PMC - PMC1217976
EDAT- 1996/12/01 00:00
MHDA- 1996/12/01 00:01
PMCR- 1997/06/01
CRDT- 1996/12/01 00:00
PHST- 1996/12/01 00:00 [pubmed]
PHST- 1996/12/01 00:01 [medline]
PHST- 1996/12/01 00:00 [entrez]
PHST- 1997/06/01 00:00 [pmc-release]
AID - 10.1042/bj3200627 [doi]
PST - ppublish
SO  - Biochem J. 1996 Dec 1;320 ( Pt 2)(Pt 2):627-34. doi: 10.1042/bj3200627.