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At least 631 records · Page 35Linked to original sources
PubMed1979

Cobalt iontophoresis of sensory nerves in the rat lung.

By iontophoretically introducing, first, cobalt and, subsequently, sulfide ions into the vagus nerve, it is possible to trace sensory nerves to their endings in the rat lung. Nerve fibers and terminals are found predominantly in the adventitia of the airways and blood vessels. Some nerves are found in the submucosa of the bronchi and bronchioles. Some are found in the cardiac muscle on the periphery of pulmonary veins, and a few nerves are seen to end among smooth muslces of the blood vessels and the airways. At least three types of nerve endings can be identified at the light microscopic level: (1) free nerve endings; (2) brush-like endings; (3) knob-like terminals.

Animals↗
PubMed1992

Neuronal maps of the frontal ganglion of the cockroach, Periplaneta americana, prepared by heavy metal iontophoresis.

Neurons in whole mount preparations of the frontal ganglion (FG) of the cockroach, Periplaneta americana, were mapped with the aid of cobalt chloride staining and silver intensification techniques. Eighty-six neurons were counted in the FG after staining with reduced methylene blue. The cell size ranged between 20 to 35 microns in diameter. Of the somata located in the FG, 44 were found to contribute their fibers to the nervus recurrens, 26 to the right frontal commissure, 28 to the left frontal commissure, and 6 to the nervus connectivus. In addition, a few neurons presumably from the tritocerebral region also contribute their fibers in the formation of nervus connectivus. The present study has helped delineate the neuronal connections of the FG with the brain and neuroendocrine system (corpora cardiaca and corpora allata). This information will be useful in facilitating the positioning of microelectrodes in our future electrophysiological experiments.

Animals↗
PubMed1988

Influence of constant current iontophoresis on the impedance and passive Na+ permeability of excised nude mouse skin.

The impedance of excised nude mouse skin was determined over the frequency range 0.2-2500 Hz. Impedance versus frequency plots were obtained for skin which had undergone progressive hydration over a period of 8 h, and for similarly hydrated skin which, during the hydration period, was also exposed to a current density of 0.16 mA cm-2 for 1 h. The parallel frequency-dependent skin resistance and capacitance were then calculated from the impedance data. The skin resistance, at 0.2 Hz, for skin exposed to the iontophoretic current decreased by a factor of approximately 5 compared with that observed for skin which had undergone hydration, implying that the current had altered the ion conducting pathways of the skin. In addition, the Na+ flux was measured and shown to be linearly correlated (r = 0.99) with the inverse of the impedance of the skin at 0.2 Hz. This implies that the low frequency impedance of the skin is a measure of the passive ion permeability of the skin, and that this technique can be used as a noninvasive way to assess the relative effects of different types of iontophoretic current on the skin.

Animals↗
PubMed1990

Transdermal iontophoresis of gonadotropin releasing hormone (LHRH) and two analogues.

Gonadotropin releasing hormone (GnRH), as well as an antagonist [Ac-D2Nal,1 D4ClPhe,2 D3Pal,3 NicLys,5 DNicLys,6 ILys,8 DAla10] GnRH.HOAc (1) and a superagonist [DTrp6, Pro9-NHEt]GnRH (2), have been electrochemically driven across excised hairless mouse skin. Determined by HPLC analysis, the delivery rate from aqueous solution into isotonic saline at 0.5 mA cm-2 was as high as 19 nM cm-2 h-1 for 2. Because of its insolubility in water, analogue 1 could only be delivered from an acidic donor solution. Analogue 2 was also delivered in pulsatile fashion using current on/off cycles. For all three peptides, passive transport was negligible and stability is evident when in contact with the stratum corneum. Slow metabolism occurs when GnRH contacts the dermal side of hairless mouse skin.

Animals↗
PubMed1993

Iontophoresis of hydrocortisone across hairless mouse skin: investigation of skin alteration.

The effects of hydration, sodium dodecyl sulfate (SDS), and electric current on the permeability of hairless mouse skin was examined in vitro with a neutral solute, hydrocortisone, as a permeant. The study was carried out by pretreating the skin with (1) normal saline, (2) 0.06% SDS in 0.3% NaCl, (3) normal saline plus 0.5 mA anodic current, and (4) 0.06% SDS in 0.3% NaCl plus 0.5 mA anodic current for 8 h. The pretreated skin was then immediately used for passive or anodic transport of hydrocortisone. Results show that pretreatment of skin with either normal saline or 0.06% SDS resulted in a slightly increased passive penetration of hydrocortisone with a prolonged lag time, but did not significantly change the anodic transport of hydrocortisone. There was no significant difference between normal saline pretreatment and 0.06% SDS pretreatment, indicating that 0.06% SDS did not irreversibly alter the permeability of skin other than its hydration effect. Pretreatment of skin with current, and especially with current combined with 0.06% SDS, yielded a significant increase in both passive and anodic transport of hydrocortisone with reduced lag time, indicating that alteration of the skin structure had occurred. The reversibility of this alteration depends on the duration of exposure of the skin to the electric field. Short-term exposure (< 2 h) does not appear to change the permeability of skin in any significant way; long-term exposure may lead to slowly reversible or irreversible skin alteration.

Animals↗
PubMed1998

Oxygen-free radicals and nitric oxide are involved in the thrombus growth produced by iontophoresis of ADP.

Thrombi have been induced by iontophoretic application of ADP on the venules of the mesentery of male Wistar rats (250-350 g). We determined the thrombus growth which is a reflection of platelet recruitment. We have demonstrated the ability of two oxygen-free radical scavengers, superoxide dismutase (SOD), a superoxide anion scavenger, and catalase, a hydrogen peroxide scavenger, to reduce thrombus growth. Imidazole, a thromboxane synthase inhibitor also reduces the thrombus growth. Dimethylthiourea, a hydroxyl radical scavenger, does not alter the thrombus size. The administration of a NO synthase inhibitor, Ng-nitro-L-arginine methyl ester (L-NAME), sharply increased the volume of the thrombus. Our results show the implication of superoxide anion, hydrogen peroxide and nitric oxide in platelet recruitment. (c) 1998 The Italian Pharmacological Society.

Adenosine Diphosphate↗
PubMed1978

Tracing of neurosecretory neurons in crayfish optic ganglia by cobalt iontophoresis.

The axonal connections between the medulla terminalis ganglionic X-organ (MTGXO) and the sinus gland are traced by iontophoretic application of cobalt dye to the neurosecretory system in the eyestalks of the crayfish, Orconectes limosus. The MTGXO consists of about 15 large perikarya, forming a distinct subgroup of neurosecretory cells in the medulla terminalis and giving rise to a prominent fibre bundle. Additional axons reaching the sinus gland from the medulla interna, the medulla externa and the optic nerve are less conspicuous.

Animals↗
PubMed1977

The effects of pH on the conductance change evoked by iontophoresis in the frog neuromuscular junction.

The amplitude of the electrophoretically evoked end-plate potential increases with changing the pH of the bathing solution from 9.4 to 5.4 at room temperature. This change is not observed at lower temperature. The underlying current (e.p.c.I) is slightly decreasing at room temperature by lowering the pH. The relationship between the amplitude of the e.p.c.I and membrane potential is highly non-linear at pH 9.4, while it is quite linear at pH 5.4. The time course of the e.p.c.I is changed neither by different pH, nor by different membrane potential. The data suggest that during the e.p.c.I, the mediator (ACh), the receptor (R) and the mediator-receptor complex are in equilibrium: the amplitude of the e.p.c.I will thus depend on the affinity constant of the reversible reaction between ACh and R. It is concluded that by decreasing the pH, the affinity constant is decreased.

Acetylcholine↗
PubMed1975

A tungsten electrode insulated by a concentric arrangement of glass-pipettes for iontophoresis.

A method is described by which electrolytically sharpened tungsten wires were coated with a coaxial assembly of 5-8 glass-capillaries. This glass coating provides good insulation and high rigidity of the tungsten electrodes. The glass pipettes were used for electrophoretic ejection of test substances and the tungsten electrode for extracellular recording of neuronal activity.

Animals↗