PMID- 8350277
OWN - NLM
STAT- MEDLINE
DCOM- 19930913
LR  - 20190512
IS  - 0022-3751 (Print)
IS  - 1469-7793 (Electronic)
IS  - 0022-3751 (Linking)
VI  - 461
DP  - 1993 Feb
TI  - Calcium accumulation by organelles within Myxicola axoplasm.
PG  - 633-46
AB  - 1. 45Ca2+ accumulation into inulin-inaccessible compartments within cytoplasm 
      from the giant axon of Myxicola infundibulum was measured as a function of free 
      calcium, pH, and time. Accumulation reached a maximum after 1 h and remained 
      stable for at least 3 h. 2. At 0.5, 5, and 50 microM [Ca2+], in the presence of 1 
      mM ATP or 5 mM succinate, steady-state calcium uptake had a bell-shaped 
      dependence on pH with a maximum near pH 7. Uptake was abolished by the proton 
      uncoupling reagent carbonyl cyanide p-trifluoromethoxy-phenylhydrazone (FCCP, 4 
      micrograms ml-1). 3. Uptake of the membrane permeant cation, 
      [14C]-tetraphenylphosphonium (TPP+), also had a bell-shaped dependence on pH with 
      a maximum pH approximately 7, suggesting a pH dependence of the electrical 
      potential of a membrane enclosed cytoplasmic compartment. Cyanide (2 mM) 
      inhibited TPP+ uptake. 4. Inositol 1,4,5-trisphosphate (IP3, 10 microM), reduced 
      steady-state calcium accumulation by 20-22% at 0.5 microM free calcium, pH 7 (P < 
      0.01, n = 16) and at 5 microM free calcium, pH 8 (P < 0.0005, n = 35). No effects 
      of IP3 were found at other pH or calcium concentrations. 5. Neither guanosine 
      5'-triphosphate (GTP) nor inositol 1,3,4,5-tetrakisphosphate (IP4) had an effect 
      on calcium uptake (5 microM [Ca2+], pH 8). 6. At 0.5 microM free calcium; 
      vanadate (10 microM) inhibited 20-30%, of the 45Ca2+ accumulation, thapsigargin 
      (33 nM) inhibited 20-30%, and cyanide (2 mM) plus oligomycin B (2 micrograms 
      ml-1), or valinomycin (1 microM), inhibited 70-80%. The fraction of uptake 
      sensitive to thapsigargin fell as the free calcium increased; however, the 
      sensitivity of uptake to cyanide plus oligomycin B was approximately 80% for 0.5, 
      5.0, and 50 microM [Ca2+]. 7. Thapsigargin had no additional inhibiting effect in 
      the presence of cyanide plus oligomycin B. IP3 had no effect in the presence of 
      cyanide plus oligomycin B or other mitochondrial inhibitors. 8. Results suggest 
      the presence of both mitochondrial (70-80%) and non-mitochondrial (20-30%) 
      calcium pools in this system (at 0.5-5.0 microM Ca2+). The apparent 
      non-mitochondrial uptake (sensitive to thapsigargin, or IP3) is not detectable in 
      the presence of mitochondrial inhibitors. We interpret these results as evidence 
      of functional communication between mitochondrial and non-mitochondrial calcium 
      stores.
FAU - al-Baldawi, N F
AU  - al-Baldawi NF
AD  - Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322.
FAU - Moore, J E
AU  - Moore JE
FAU - Abercrombie, R F
AU  - Abercrombie RF
LA  - eng
GR  - NIH NS19194/NS/NINDS NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - J Physiol
JT  - The Journal of physiology
JID - 0266262
RN  - 0 (Terpenes)
RN  - 3WHH0066W5 (Vanadates)
RN  - 67526-95-8 (Thapsigargin)
RN  - 85166-31-0 (Inositol 1,4,5-Trisphosphate)
RN  - 86-01-1 (Guanosine Triphosphate)
RN  - 9005-49-6 (Heparin)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Axons/*metabolism
MH  - Biological Transport/drug effects
MH  - Calcium/*metabolism
MH  - Guanosine Triphosphate/pharmacology
MH  - Heparin/pharmacology
MH  - Hydrogen-Ion Concentration
MH  - In Vitro Techniques
MH  - Inositol 1,4,5-Trisphosphate/pharmacology
MH  - Mitochondria/physiology
MH  - Organelles/*metabolism
MH  - Polychaeta/*metabolism
MH  - Terpenes/pharmacology
MH  - Thapsigargin
MH  - Vanadates/pharmacology
PMC - PMC1175277
EDAT- 1993/02/01 00:00
MHDA- 1993/02/01 00:01
PMCR- 1993/02/01
CRDT- 1993/02/01 00:00
PHST- 1993/02/01 00:00 [pubmed]
PHST- 1993/02/01 00:01 [medline]
PHST- 1993/02/01 00:00 [entrez]
PHST- 1993/02/01 00:00 [pmc-release]
AID - 10.1113/jphysiol.1993.sp019533 [doi]
PST - ppublish
SO  - J Physiol. 1993 Feb;461:633-46. doi: 10.1113/jphysiol.1993.sp019533.