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C R House

Publications and source records attributed to C R House.

51 records · Page 3Linked to original sources
PubMed1974

Conductance changes associated with the secretory potential in the cockroach salivary gland.

1. Conductance changes in the acini of the cockroach salivary gland have been examined during nerve stimulation by means of two intracellular electrodes placed in the same acinus, the first electrode being used for recording membrane potential and the second for current injection.2. The transient hyperpolarization (secretory potential) in the acinus evoked by nerve stimuli is accompanied by a rise in membrane conductance. The conductance, however, remains high for a longer period than that of the response.3. Applying the analysis of Trautwein & Dudel (1958) to the secretory potentials recorded in the acinus (assumed to behave electrically like a single cell) gives estimates of the ;transmitter equilibrium potential'. The values indicate that the neurotransmitter increases the membrane potassium conductance.4. The hyperpolarization of the acinus evoked by 10(-6)M dopamine in the bathing fluid is also associated with an increase in membrane potassium conductance.

Animals↗
PubMed1971

The effect of different ionic levels on the electrical response of toad skin to noradrenaline.

1. After the addition of noradrenaline (final concentration 4 x 10(-5)M) to the inner medium of isolated toad skins, they underwent a depolarization (inner surface becoming less positive) followed by a hyperpolarization.2. The dependence of the minimal and maximal levels of the depolarizing and hyperpolarizing phases of the response upon the external concentrations of sodium and chloride ions was examined.3. The experimental data were considered to support the view that the hyperpolarization was generated by an increase in the sodium to chloride permeability ratio for the outer barrier of the skin and that the depolarization resulted from a transient increase in the conductance of transient shunt pathways in the skin.4. When the external sodium and chloride ions were replaced by magnesium (or potassium) and sulphate ions, noradrenaline initiated a transient hyperpolarization. During this hyperpolarizing response the time course of the change in the skin's conductance resembled that of the skin potential. The polarity of the response was changed by reversing the chloride concentration gradient across the skin.5. The dependence of the maximal level of the hyperpolarizing response upon the internal potassium concentration was examined.6. It was concluded that the hyperpolarizing response was generated partially by an increase in the potassium to chloride permeability ratio for the inner barrier of the skin and predominantly by the movement of chloride and accompanying cations through a transient shunt pathway, probably the active glands.

Animals↗
PubMed1970

The effect of noradrenaline on the toad skin potential.

1. The electrical response of isolated toad skins to the presence of 4 x 10(-5)M noradrenaline in the inner medium has been studied.2. When skins were bathed in Ringer solution, noradrenaline initiated a partial depolarization of the skin potential (inside surface becoming less positive) followed by a hyperpolarization; however, noradrenaline depolarized skins in sulphate Ringer.3. The origin of the hyperpolarizing phase of the response to noradrenaline was studied by comparing the size of perturbations in the skin potential, produced by identical changes in external sodium, external chloride or internal potassium concentrations, before and during the response to noradrenaline.4. Measurements of skin conductance were made in different sulphate media in order to estimate the magnitudes of the conductance of the shunt pathway through the skin and the conductance of the pathway for actively transported sodium ions.5. Interpretation of both the variations in the perturbations of skin potential and the skin conductance measurements led to the conclusion that the hyperpolarizing phase of the response to noradrenaline was generated by an increase in the sodium to chloride permeability ratio for the outer barrier. It was considered that other evidence was compatible with this view.6. Similar experimental methods were employed to study the action of antidiuretic hormone (ADH) and an elevated external concentration of calcium on the outer barrier. It was found that ADH increased the sodium to chloride permeability ratio whereas calcium decreased it. The separate actions of ADH and calcium on the sodium permeability of the outer barrier did not interfere apparently with the subsequent ability of noradrenaline to increase the sodium to chloride permeability ratio for this barrier in the skin.

Animals↗
PubMed1969

The role of glandular activity in the electrical response of amphibian skin to noradrenaline.

1. The electrical response of isolated amphibian skins to the presence of 4 x 10(-5)M noradrenaline in the inner medium has been studied.2. The response to noradrenaline consists of a transient secretion from the skin glands, a transient increase in the short-circuit current, a transient decrease in the skin resistance and a partial depolarization of the skin potential (inside surface becoming less positive) followed by a hyperpolarization.3. The origin of the initial depolarizing phase of the response to noradrenaline has been studied.4. It is considered that the initial depolarization results partially from an increase in the chloride permeability of the outer membranes of the epithelial cells and predominantly from the emergence of an additional transient shunt pathway in the skin.5. It is proposed that during secretory activity the skin glands constitute the transient shunt pathway responsible for the initial depolarizing phase of the response to noradrenaline.

Animals↗
PubMed1966

Unstirred layers in frog skin.

1. Estimates of the magnitudes of the unstirred regions associated with isolated frog skin in sulphate Ringer's solution have been made under different stirring conditions.2. The method of investigation was an analysis of the time course of the p.d. transients which occurred when external sodium concentration and internal potassium concentration changes were made in the bathing solution.3. Making an arbitrary but reasonable assumption about the diffusional coefficient of Na(2)SO(4) in the outer unstirred region, the magnitudes of the outer unstirred layers were found to lie within the ranges 40-60 mu, 30-50 mu and 30-40 mu under stirring conditions of 120, 300 and 500 rev/min, respectively.4. Making an arbitrary but reasonable assumption about the diffusion coefficient of K(2)SO(4) in the inner unstirred region, the magnitudes of the inner unstirred layers were found to lie within the ranges 150-230 mu, 120-200 mu and 100-170 mu under stirring conditions of 120, 300 and 500 rev/min, respectively.

Animals↗
PubMed1966

An examination of the evidence for membrane pores in frog skin.

1. Measurements of the diffusional permeability, P(d), of tritiated water in isolated frog skin bathed in sulphate Ringer have been made under different stirring conditions.2. The mean +/- S.E. values for P(d) were found to be (6.5 +/- 0.3), (7.9 +/- 0.5), (9.7 +/- 0.7) and (11.1 +/- 0.8) x 10(-5) cm sec(-1) at 120, 300, 500 and 1000 rev/min. It is considered that these results indicate the existence of ;unstirred layers' associated with frog skin.3. The hydraulic conductivity, L(p), of the skin in sulphate Ringer was found to be (2.36 +/- 0.07) x 10(-7) cm sec(-1) atm(-1) (+/- S.E. of estimate), and no marked increase in this value for L(p) was found when the stirring rate was increased from 0 to 500 rev/min.4. It is considered that these results show that previous comparisons of the relative magnitudes of L(p)RT/V(w) (where V(w) is the partial molar volume of water) and P(d) for frog skin have been in error because of the presence of ;unstirred layers'.5. The bearing of our results and other evidence on the question of pores in cell membranes has been discussed.

Animals↗