PMID- 12010640
OWN - NLM
STAT- MEDLINE
DCOM- 20020625
LR  - 20191210
IS  - 0022-0795 (Print)
IS  - 0022-0795 (Linking)
VI  - 173
IP  - 2
DP  - 2002 May
TI  - Muscarinic acetylcholine receptor activation induces Ca2+ mobilization and 
      Na+/K+-ATPase activity inhibition in eel enterocytes.
PG  - 325-34
AB  - The effect of carbachol (Cch) on intracellular calcium concentration ([Ca2+]i) in 
      eel enterocytes was examined using the fluorescent Ca2+ indicator fura-2. Cch 
      caused a biphasic increase in [Ca2+]i, with an initial spike followed by a 
      progressively decreasing level (over 6 min) to the initial, pre-stimulated, 
      level. The effect of Cch was dose-dependent with a 7.5-fold increase in [Ca2+]i 
      over basal level induced by the maximal dose of Cch (100 microM). In 
      Ca2+-free/EGTA buffer the effect of Cch was less pronounced and the [Ca2+]i 
      returned rapidly to basal levels. The increment of [Ca2+]i was dose-dependently 
      attenuated in cells pre-treated with U73122, a specific inhibitor of 
      phospholipase C, suggesting that the Cch-stimulated increment of [Ca2+]i required 
      inositol triphosphate formation. In the presence of extracellular Ca2+, 
      thapsigargin (TG), a specific microsomal Ca2+-ATPase inhibitor, caused a 
      sustained rise in [Ca2+]i whereas in Ca2+-free medium the increase in [Ca2+]i was 
      transient; in both cases, subsequent addition of Cch was without effect. When 2 
      mM CaCl2 were added to the cells stimulated with TG or with Cch in Ca2+-free 
      medium, a rapid increase in [Ca2+]i was detected, corresponding to the 
      capacitative Ca2+ entry. Thus, both TG and Cch depleted intracellular Ca2+ stores 
      and stimulated influx of extracellular Ca2+ consistent with capacitative Ca2+ 
      entry. K+ depolarization obtained with increasing concentrations of KCl in the 
      extracellular medium induced a dose-related increase in [Ca2+]i which was blocked 
      by 2 microM nifedipine, a non-specific L-type Ca2+ channel blocker. Nifedipine 
      also changed significantly the height of the Ca2+ transient, and the rate of 
      decrement to the pre-stimulated [Ca2+]i level, indicating that Ca2+ entry into 
      enterocytes also occurs through an L-type voltage-dependent calcium channel 
      pathway. We also show that isolated enterocytes stimulated with increasing Cch 
      concentrations (0.1-1000 microM) showed a dose-dependent inhibition of the 
      Na+/K+-ATPase activity. The threshold decrease was at 1 microM Cch; it reached a 
      maximum at 100 microM (50.5% inhibition) and did not decrease further with the 
      use of higher dose. The effect of Cch on Na+/K+-ATPase activity was dependent on 
      both protein kinase C (PKC) and protein phosphatase calcineurin activation since 
      the PKC inhibitor calphostin C abolished Cch effects, while the calcineurin 
      inhibitor FK506 augmented Cch effect. Collectively, these data establish a 
      functional pathway by which Cch can modulate the activity of the Na+/K+-ATPase 
      through a PKC-dependent (calphostin C-sensitive) pathway and a 
      calcineurin-dependent (FK506-sensitive) pathway.
FAU - Muscella, A
AU  - Muscella A
AD  - Physiology Laboratory, Department of Biology, University of Lecce, 73100 Lecce, 
      Italy.
FAU - Greco, S
AU  - Greco S
FAU - Elia, M G
AU  - Elia MG
FAU - Jimenez, E
AU  - Jimenez E
FAU - Storelli, C
AU  - Storelli C
FAU - Marsigliante, S
AU  - Marsigliante S
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - England
TA  - J Endocrinol
JT  - The Journal of endocrinology
JID - 0375363
RN  - 0 (Calcineurin Inhibitors)
RN  - 0 (Calcium Channel Blockers)
RN  - 0 (Cholinergic Agonists)
RN  - 0 (Enzyme Inhibitors)
RN  - 0 (Naphthalenes)
RN  - 0 (Receptors, Cholinergic)
RN  - 0 (calphostin complex)
RN  - 67526-95-8 (Thapsigargin)
RN  - 8Y164V895Y (Carbachol)
RN  - 9NEZ333N27 (Sodium)
RN  - EC 2.7.11.13 (Protein Kinase C)
RN  - EC 3.1.4.- (Type C Phospholipases)
RN  - EC 7.2.2.10 (Calcium-Transporting ATPases)
RN  - EC 7.2.2.13 (Sodium-Potassium-Exchanging ATPase)
RN  - I9ZF7L6G2L (Nifedipine)
RN  - SY7Q814VUP (Calcium)
RN  - W36ZG6FT64 (Sirolimus)
RN  - WM0HAQ4WNM (Tacrolimus)
SB  - IM
MH  - Analysis of Variance
MH  - Animals
MH  - Calcineurin Inhibitors
MH  - Calcium/*metabolism
MH  - Calcium Channel Blockers/pharmacology
MH  - Calcium-Transporting ATPases/antagonists & inhibitors
MH  - Carbachol/*pharmacology
MH  - Cholinergic Agonists/*pharmacology
MH  - Dose-Response Relationship, Drug
MH  - Eels
MH  - Enterocytes/drug effects/*metabolism
MH  - Enzyme Activation/drug effects
MH  - Enzyme Inhibitors/pharmacology
MH  - Naphthalenes/pharmacology
MH  - Nifedipine/pharmacology
MH  - Protein Kinase C/antagonists & inhibitors
MH  - Receptors, Cholinergic/*metabolism
MH  - Sirolimus/pharmacology
MH  - Sodium/metabolism
MH  - Sodium-Potassium-Exchanging ATPase
MH  - Tacrolimus/pharmacology
MH  - Thapsigargin/pharmacology
MH  - Type C Phospholipases/antagonists & inhibitors
EDAT- 2002/05/16 10:00
MHDA- 2002/06/26 10:01
CRDT- 2002/05/16 10:00
PHST- 2002/05/16 10:00 [pubmed]
PHST- 2002/06/26 10:01 [medline]
PHST- 2002/05/16 10:00 [entrez]
AID - JOE04381 [pii]
AID - 10.1677/joe.0.1730325 [doi]
PST - ppublish
SO  - J Endocrinol. 2002 May;173(2):325-34. doi: 10.1677/joe.0.1730325.