Interaction between carbachol and vasoactive intestinal peptide in cells of isolated colonic crypts

1992 ◽  
Vol 262 (5) ◽  
pp. G940-G944
Author(s):  
L. Greenwald ◽  
B. A. Biagi
Keyword(s):  
Vasoactive Intestinal Peptide ◽  
Chloride Transport ◽  
Basolateral Membrane ◽  
Distal Colon ◽  
Equilibrium Potential ◽  
Colonic Crypts ◽  
Intracellular K Activity ◽  
Crypt Cells ◽  
Basolateral Membrane Potential ◽  
K Activity

In a previous study [B. Biagi, Y.-Z. Wang, and H. J. Cooke, Am. J. Physiol. 258 (Gastrointest. Liver Physiol. 21): G223-G230, 1990], carbachol stimulated active chloride transport in rabbit distal colon, yet had no effect on the basolateral membrane potential (Vbl) of cells from isolated crypts from the same tissue. In the present study, crypt cells were first depolarized with vasoactive intestinal peptide (VIP; 1 x 10(-9) M) (control Vbl = -62 mV; VIP Vbl = -48 mV) and then exposed to carbachol in the presence of VIP. The VIP-induced depolarization of Vbl was completely reversed by carbachol (0.1 mM; repolarization to -65 mV). Similar repolarization was seen by applying carbachol to crypt cells depolarized by 10 mM aminophylline. Intracellular K+ activity (aiK), measured with K(+)-selective microelectrodes, was 64.3 mM (concn = 85 mM), yielding a K+ equilibrium potential (EK+) of -76 mV. Neither carbachol nor VIP application caused significant changes in aiK. These results demonstrate the presence of cholinergic receptors on colonic crypt cells. The magnitude of the carbachol effect on Vbl is greater when Vbl is depolarized relative to EK+. The results are consistent with the hypothesis that carbachol acts by increasing basolateral K+ conductance, driving the cell toward the EK+.

scholarly journals Intracellular K+ activity and its relation to basolateral membrane ion transport in Necturus gallbladder epithelium.

1980 ◽  
Vol 76 (1) ◽  
pp. 33-52 ◽  
Author(s):  
L Reuss ◽  
S A Weinman ◽  
T P Grady
Keyword(s):  
Cell Membrane ◽  
Amphotericin B ◽  
Basolateral Membrane ◽  
Membrane Potentials ◽  
Equilibrium Potential ◽  
Gallbladder Epithelium ◽  
Bathing Medium ◽  
Necturus Gallbladder ◽  
Intracellular K Activity ◽  
K Activity

A study of the mechanisms of the effects of amphotericin B and ouabain on cell membrane and transepithelial potentials and intracellular K activity (alpha Ki) of Necturus gallbladder epithelium was undertaken with conventional and K-selective intracellular microelectrode techniques. Amphotericin B produced a mucosa-negative change of transepithelial potential (Vms) and depolarization of both apical and basolateral membranes. Rapid fall of alpha Ki was also observed, with the consequent reduction of the K equilibrium potential (EK) across both the apical and the basolateral membrane. It was also shown that, unless the mucosal bathing medium is rapidly exchanged, K accumulates in the unstirred fluid layers near the luminal membrane generating a paracellular K diffusion potential, which contributes to the Vms change. Exposure to ouabain resulted in a slow decrease of alpha Ki and slow depolarization of both cell membranes. Cell membrane potentials and alpha Ki could be partially restored by a brief (3-4 min) mucosal substitution of K for Na. Under all experimental conditions (control, amphotericin B, and ouabain), EK at the basolateral membrane was larger than the basolateral membrane equivalent emf (Eb). Therefore, the K chemical potential difference appears to account for Eb and the magnitude of the cell membrane potentials, without the need to postulate an electrogenic Na pump. Comparison of the rate of Na transport across the tissue with the electrodiffusional K flux across the basolateral membrane indicates that maintenance of a steady-state alpha Ki cannot be explained by a simple Na,K pump-K leak model. It is suggested that either a NaCl pump operates in parallel with the Na,K pump, or that a KCl downhill neutral extrusion mechanism exists in addition to the electrodiffusional K pathway.

Potassium distribution and membrane potential of sensory neurons in the leech nervous system

1984 ◽  
Vol 51 (4) ◽  
pp. 689-704 ◽  
Author(s):  
W. R. Schlue ◽  
J. W. Deitmer
Keyword(s):  
Nervous System ◽  
Membrane Potential ◽  
Sensory Neurons ◽  
Membrane Resistance ◽  
Equilibrium Potential ◽  
Bathing Medium ◽  
Membrane Hyperpolarization ◽  
K Concentration ◽  
Intracellular K Activity ◽  
K Activity

The intracellular K activity (aKi) and membrane potential of sensory neurons in the leech central nervous system were measured in normal and altered external K+ concentrations, [K+]o, using double-barreled, liquid ion-exchanger microelectrodes. In control experiments membrane potential measurements were made using potassium chloride-filled single-barreled microelectrodes. All values are means +/- SD. At the normal [K+]o (4 mM) the mean aKi of all cells tested was 72.6 +/- 10.6 mM (n = 40) and the average membrane potential was -47.3 +/- 5.2 mM (n = 40). When measured with single-barreled microelectrodes, the membrane potential averaged -45.3 +/- 2.9 mV (n = 12). Assuming an intracellular K+ activity coefficient of 0.75, the intracellular K+ concentration of sensory neurons would be 96.8 +/- 14.1 mM). With an extracellular K+ concentration of 5.8 mM in the intact ganglion compared to the K+ concentration of 4 mM in the bath, the K+ equilibrium potential was -71.5 mV. When the ganglion capsule was opened, the extracellular K+ concentrations in the ganglion were similar to that of the bathing medium and the calculated K+ equilibrium potential was -81 mV. The membrane of sensory neurons depolarized following the changes to elevated [K+]o (greater than or equal to 10-100 mM), whereas aKi changed only little or not at all. At very low [K+]o (0.2, 0 mM) aKi and membrane potential showed little short-term (less than 3 min) effect but began to change after longer exposure (greater than 3 min). Reduction of [K+]o from 4 to 0.2 mM (or 0 mM) produced first a slow, and then a more rapid decrease of aKi and membrane resistance, accompanied by a slow membrane hyperpolarization. Following readdition of normal [K+]o, the membrane first depolarized and then transiently hyperpolarized, eventually returning slowly to the normal membrane potential.(ABSTRACT TRUNCATED AT 400 WORDS)

Microelectrode measurements of K+ and pH in rabbit gastric glands: effect of histamine

1984 ◽  
Vol 246 (4) ◽  
pp. G433-G444
Author(s):  
K. Kafoglis ◽  
S. J. Hersey ◽  
J. F. White
Keyword(s):  
Membrane Potential ◽  
Ion Exchange ◽  
Basolateral Membrane ◽  
Free Medium ◽  
Na Transport ◽  
K Uptake ◽  
Gastric Glands ◽  
Microelectrode Measurements ◽  
Intracellular K Activity ◽  
K Activity

Conventional and liquid ion-exchange microelectrodes sensitive to K+ or pH were used to examine the response of isolated rabbit gastric glands to histamine. The epithelial cells were impaled across the basolateral membrane. The membrane potential averaged -6.1 +/- 0.6 mV and was unchanged after replacement of medium K+, Cl-, or Na+. The intracellular K+ activity (alpha iK) averaged 41.3 +/- 3.0 mM, indicating K+ accumulation by a factor of 6.8. Active accumulation of K+ was eliminated by ouabain. In contrast, histamine increased K+ activity to 55.3 +/- 3.9 mM. This stimulation was blocked by ouabain. In glands bathed in a Na+-free medium containing ouabain, addition of histamine elevated alpha iK from 12.5 +/- 0.7 to 17.1 +/- 1.1 mM. Isobutylmethylxanthine (10(-4) M) also elevated alpha iK. When impaled with pH-sensitive microelectrodes, glands exposed to histamine exhibited regions of acidity as low as pH 3. Acidification was also produced by histamine after medium Na+ had been replaced with choline. Picoprazole (H 149/94) blocked the effects of histamine on alpha iK and gland pH. The results are consistent with the view that histamine-induced acid secretion by gastric glands is associated with K+ uptake by a mechanism that is independent of Na+ transport but is inhibited by intracellular Na+. This is most likely the H+-K+-ATPase on the secretory surface of the gland cells. Evidence that some tissue K+ is bound or compartmentalized is also discussed.

scholarly journals The effect of extracellular potassium on the intracellular potassium ion activity and transmembrane potentials of beating canine cardiac Purkinje fibers.

1977 ◽  
Vol 69 (4) ◽  
pp. 463-474 ◽  
Author(s):  
D S Miura ◽  
B F Hoffman ◽  
M R Rosen
Keyword(s):  
Equilibrium Potential ◽  
Extracellular Potassium ◽  
Purkinje Fibers ◽  
Transmembrane Potentials ◽  
Cardiac Purkinje Fibers ◽  
K Concentration ◽  
Range Of Values ◽  
Intracellular K Activity ◽  
Liquid Ion Exchanger ◽  
K Activity

We used open tip microelectrodes containing a K+-sensitive liquid ion exchanger to determine directly the intracellular K+ activity in beating canine cardiac Purkinje fibers. For preparations superfused with Tyrode's solution in which the K+ concentration was 4.0 mM, intracellular K+ activity (ak) was 130.0+/-2.3 mM (mean+/-SE) at 37 degrees C. The calculated K+ equilibrium potential (EK) was -100.6+/-0.5 mV. Maximum diastolic potential (ED) and resting transmembrane potential (EM) were measured with conventional microelectrodes filled with 3 M KCl and were -90.6+/-0.3 and -84.4+/-0.4 mV, respectively. When [K+]o was decreased to 2.0 mM or increased to 6.0, 10.0, and 16.0 mM, ak remained the same. At [K+]o=2.0, ED was -97.3+/-0.4 and Em -86.0+/-0.7 mV; at [K+]o=16.0, ED fell to -53.8+/-0.4 mV and Em to the same value. Over this range of values for [K+]o, EK changed from -119.0+/-0.3 to -63.6+/-0.2 mV. These values for EK are consistent with those previously estimated indirectly by other techniques.

Measurements of the Intracellular Potassium Activity of Retzius Cells in the Leech Central Nervous System

1981 ◽  
Vol 91 (1) ◽  
pp. 87-101
Author(s):  
JOACHIM W. DEITMER ◽  
WOLF R. SCHLUE
Keyword(s):  
Cell Membrane ◽  
External Solution ◽  
Equilibrium Potential ◽  
The Mean ◽  
K Concentration ◽  
Retzius Cells ◽  
Intracellular K Activity ◽  
K Permeability ◽  
K Activity ◽  
External K

The intracellular K activity of leech Retzius cells was measured using double-barrelled, liquid ion exchanger, microelectrodes. At the normal external K+ concentration of 4 mm (equivalent to 3 mm-K activity, assuming an activity coefficient of 0.75) the mean K activity was 101.3 ± 7.6 mm (S.D., n = 14) in the cell bodies, and 4.35 ± 0.4 mV (n = 27) in the extracellular spaces surrounding them, indicating a K+ equilibrium potential of - 80 mV. The mean membrane potential was - 43.6 + 4.9 mV (n = 14). In a K-free external solution, or in the presence of 5 × 10−4m-ouabain, the intracellular K activity decreased by up to 14 mm min−1. This indicates an efflux of K+ ions across the cell membrane of approximately 2 × 10−10 mol cm−2s, and an apparent K+ permeability coefficient of 8 × 10−8 cms−1. The cell membrane depolarized upon removal of K+ and upon addition of ouabain, and transiently hyperpolarized beyond its initial level on return to the normal external K+ concentration. The recovery from this hyperpolarization paralleled the increase of the intracellular K activity following the re-addition of K+. Our results suggest that, despite the high K+ permeability of the Retzius cell membrane, the intracellular K activity is maintained at a high level by an electrogenic pump.

Differential localization of colonic H+-K+-ATPase isoforms in surface and crypt cells

1998 ◽  
Vol 274 (2) ◽  
pp. G424-G429 ◽  
Author(s):  
Vazhaikkurichi M. Rajendran ◽  
Satish K. Singh ◽  
John Geibel ◽  
Henry J. Binder
Keyword(s):  
Spatial Distribution ◽  
Atpase Activity ◽  
Distal Colon ◽  
Compelling Evidence ◽  
Α Subunit ◽  
Colonic Crypts ◽  
Rat Distal Colon ◽  
Acid Load ◽  
Apical Membranes ◽  
Crypt Cells

Two distinct colonic H+-K+-adenosinetriphosphatase (H+-K+-ATPase) isoforms can be identified in part on the basis of their sensitivity to ouabain. The colonic H+-K+-ATPase α-subunit (HKcα) was recently cloned, and its message and protein are present in surface (and the upper 20% of crypt) cells in the rat distal colon. These studies were performed to establish the spatial distribution of the ouabain-sensitive and ouabain-insensitive components of both H+-K+-ATPase activity in apical membranes prepared from surface and crypt cells and K+-dependent intracellular pH (pHi) recovery from an acid load both in isolated perfused colonic crypts and in surface epithelial cells. Whereas H+-K+-ATPase activity in apical membranes from surface cells was 46% ouabain sensitive, its activity in crypt apical membranes was 96% ouabain sensitive. Similarly, K+-dependent pHi recovery in isolated crypts was completely ouabain sensitive, whereas in surface cells K+-dependent pHi recovery was insensitive to ouabain. These studies provide compelling evidence that HKcα encodes the colonic ouabain-insensitive H+-K+-ATPase and that a colonic ouabain-sensitive H+-K+-ATPase isoform is present in colonic crypts and remains to be cloned and identified.

K activity of CCD principal cells from normal and DOCA-treated rabbits

1989 ◽  
Vol 256 (1) ◽  
pp. F136-F142 ◽  
Author(s):  
S. C. Sansom ◽  
S. Agulian ◽  
S. Muto ◽  
V. Illig ◽  
G. Giebisch
Keyword(s):  
Driving Forces ◽  
Basolateral Membrane ◽  
Cell Secretion ◽  
Principal Cells ◽  
K Secretion ◽  
Intracellular K Activity ◽  
K Transport ◽  
Liquid Ion Exchanger ◽  
Electrochemical Equilibrium ◽  
K Activity

We used liquid ion exchanger and conventional microelectrodes to evaluate the effects of mineralocorticoids on the intracellular K activity (aiK) and K transport properties of principal cells (PC) of isolated cortical collecting ducts (CCDs). Hoffman modulation optics and electrophysiological methods were used to identify PC. K activity was measured with two single-barreled electrodes. We found that aiK of PC from deoxycorticosterone acetate (DOCA)-treated rabbits (97.6 mM) was not different from controls (94.8 mM). The driving forces for K transport across the basolateral membrane favored cell to bath (reabsorption) in PCs from controls and bath to cell (secretion) in PCs from DOCA-treated rabbits. However, the driving force for K secretion across the apical membrane was not significantly different between the two groups. We used the intracellular aiKs and bath ion substitutions (gluconate for Cl and K for Na) to evaluate the effects of DOCA on the ion-selective properties of the basolateral membrane of PC. DOCA increased PK/PCl from 0.33 to 0.89. Our conclusion was as follows: in PC of control rabbits K is above electrochemical equilibrium across the basolateral membrane. However, the basolateral K conductance is probably too small for significant K recycling. In PC of DOCA-treated rabbits the aiK is below electrochemical equilibrium across the basolateral membrane and the K conductance is increased. These effects enhance K secretion across this border while maintaining cell K constant.

Stimulation of Cl permeability in colonic crypts of Lieberkuhn measured with a fluorescent indicator

1993 ◽  
Vol 265 (3) ◽  
pp. G423-G431 ◽  
Author(s):  
D. R. Halm ◽  
K. L. Kirk ◽  
K. C. Sathiakumar
Keyword(s):  
Epithelial Cell ◽  
Distal Colon ◽  
Cell Type ◽  
Fluorescent Indicator ◽  
Epithelial Cell Type ◽  
Colonic Crypts ◽  
Pg E2 ◽  
Crypt Cells ◽  
Stimulation Of ◽  
Cl Permeability

Crypts of Lieberkuhn were isolated from rabbit distal colon and the halide-sensitive dye 6-methoxy-N-[3-sulfopropyl]quinolinium was used to monitor changes in cell Cl by fluorescence microscopy. Distal colon from rabbits actively secretes Cl and K when stimulated with prostaglandin (PG) E2 but secretes only K in response to epinephrine. The secretagogues PGE2 and epinephrine each produced transient decreases of the apparent cell Cl concentration in about one-half of the crypt cells. Permeability to Cl was assessed by brief substitutions with gluconate or Br in the bath. After stimulation of secretion by PGE2 or epinephrine, Cl efflux and Br influx were increased but only in the cells that exhibited the decrease in cell Cl at the onset of stimulation. Although Cl efflux during gluconate substitution was stimulated similarly with either PGE2 or epinephrine, epinephrine stimulation led to a lower apparent Cl concentration after 2 min of gluconate substitution. Together these results support the concept that a particular epithelial cell type in the crypts responds to secretagogues and that the Cl permeability pathways differ between the secretory states induced by PGE2 and epinephrine.

Effect of sugars and amino acids on amphibian intestinal Cl- transport and intracellular Na+, K+, and Cl- activity

1986 ◽  
Vol 250 (1) ◽  
pp. G109-G117
Author(s):  
J. F. White ◽  
K. Burnup ◽  
D. Ellingsen
Keyword(s):  
Cellular Level ◽  
Equilibrium Potential ◽  
Cl Transport ◽  
Luminal Membrane ◽  
Intracellular Na Activity ◽  
The Difference ◽  
Effect Of Glucose ◽  
Intracellular K Activity ◽  
Intestinal Ion Transport ◽  
K Activity

The effect of glucose, galactose, and valine on intestinal Cl- transport and intracellular Cl-, Na+, and K+ activity was investigated in isolated segments of Amphiuma small intestine. By use of double-barreled Cl- -specific microelectrodes, it was observed that galactose and valine reduced the luminal membrane potential (psi m) and eliminated the difference between the Cl- equilibrium potential (ECl) and psi m, i.e., the Cl- accumulation potential (ECl-psi m) approached zero. Simultaneously, Cl- absorption (JnetCl) was reduced in short-circuited tissues and Na+ absorption was enhanced. In contrast, after exposure to glucose, psi m and ECl-psi m declined only transiently and JnetCl was unaltered. In tissues pretreated with galactose to reduce Cl- transport, addition of glucose to the serosal medium restored Cl- accumulation across the luminal membrane and the Cl- absorptive current. Glucose, galactose, and valine each reduced intracellular K+ activity significantly. Galactose and valine each increased [corrected] intracellular Na activity (aiNa) markedly, whereas glucose increased aiNa only slightly. In conclusion, intestinal ion transport can be limited by the availability of metabolic substrate. The nonmetabolized solutes galactose and valine inhibited Cl- uptake and net Cl- absorption while stimulating net Na absorption, as though net Na+ absorption has priority over Cl- transport at the cellular level. Cl- transport is reduced at both mucosal and serosal membranes. At the luminal membrane electrogenic Cl- uptake is slowed or a backleak of Cl- is enhanced; at the serosal membrane Cl- exchange with Na+ (and HCO3-) driven by the Na+ gradient is reduced. The availability of metabolizable glucose to the cell prevents the reduction in net Cl- absorption.

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