PMID- 9458737
OWN - NLM
STAT- MEDLINE
DCOM- 19980219
LR  - 20190509
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 274
IP  - 1
DP  - 1998 Jan
TI  - Neuronal swelling and surface area regulation: elevated intracellular calcium is 
      not a requirement.
PG  - C272-81
LID - 10.1152/ajpcell.1998.274.1.C272 [doi]
AB  - Neurons are mechanically robust. During prolonged swelling, molluscan neurons can 
      triple their apparent membrane area. They gain surface area and capacitance 
      independent of extracellular Ca concentration ([Ca]e), but it is unknown if an 
      increase in intracellular Ca concentration ([Ca]i) is necessary. If Ca for 
      stimulating exocytosis is unnecessary, it is possible that swelling-induced 
      membrane tension changes directly trigger surface area readjustments. If, 
      however, Ca-mediated but not tension-mediated membrane recruitment is responsible 
      for surface area increases, swelling neurons should sustain elevated levels of 
      [Ca]i. The purpose of this investigation is to determine if the [Ca]i in swelling 
      neurons attains levels high enough to promote exocytosis and if any such increase 
      is required. Lymnaea neurons were loaded with the Ca concentration indicator fura 
      2. Calibration was performed in situ using 4-bromo-A-23187 and Ca-ethylene 
      glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), with free Ca 
      concentration ranging from 0 to 5 microM. Swelling perturbations (medium 
      osmolarity reduced to 25% for 5 min) were done at either a standard [Ca]e or very 
      low [Ca]e level (0.9 mM or 0.13 microM, respectively). In neither case did the 
      [Ca]i increase to levels that drive exocytosis. We also monitored 
      osmomechanically driven membrane dynamics [swelling, then formation and reversal 
      of vacuole-like dilations (VLDs)] with the [Ca]i clamped below 40 nM via 
      1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). [Ca]i did not 
      change with swelling, and VLD behavior was unaffected, consistent with 
      tension-driven, [Ca]i-independent surface area adjustments. In addition, neurons 
      with [Ca]i clamped at 0.1 microM via an ionophore could produce VLDs. We conclude 
      that, under mechanical stress, neuronal membranes are compliant by virtue of 
      surface area regulatory adjustments that operate independent of [Ca]i. The 
      findings support the hypothesis that plasma membrane area is regulated in part by 
      membrane tension.
FAU - Herring, T L
AU  - Herring TL
AD  - Department of Biology, University of Ottawa, Ontario, Canada.
FAU - Slotin, I M
AU  - Slotin IM
FAU - Baltz, J M
AU  - Baltz JM
FAU - Morris, C E
AU  - Morris CE
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 37H9VM9WZL (Calcimycin)
RN  - 526U7A2651 (Egtazic Acid)
RN  - 76455-48-6 (4-bromo-A-23187)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Calcimycin/analogs & derivatives/pharmacology
MH  - Calcium/*metabolism
MH  - Cell Membrane/drug effects/physiology
MH  - Egtazic Acid/pharmacology
MH  - Ganglia, Invertebrate/cytology/*physiology
MH  - In Vitro Techniques
MH  - Lymnaea
MH  - Neurons/*cytology/drug effects/*physiology
MH  - Surface Properties
MH  - Vacuoles/physiology/ultrastructure
EDAT- 1998/02/12 00:00
MHDA- 1998/02/12 00:01
CRDT- 1998/02/12 00:00
PHST- 1998/02/12 00:00 [pubmed]
PHST- 1998/02/12 00:01 [medline]
PHST- 1998/02/12 00:00 [entrez]
AID - 10.1152/ajpcell.1998.274.1.C272 [doi]
PST - ppublish
SO  - Am J Physiol. 1998 Jan;274(1):C272-81. doi: 10.1152/ajpcell.1998.274.1.C272.