Iontophoresis type

In addition to blood, certain types of specimens are submitted to the Pediatric laboratory which would not be commonly seen elsewhere. An example of this is sweat for analysis of chloride. The process of obtaining the sweat by iontophoresis usually falls to the personnel of the Laboratory of Neonatology (17). Stool for analysis of lipids and trypsin is more commonly submitted to the Laboratory of Neonatology than to the laboratory which services the adult population. The reason for this is that one is screening for certain intestinal diseases characteristic of infants and newborns which are rare in adults. Such conditions would be celiac disease, cystic fibrosis and others. 

The nicotinic receptors on the neuromuscular end plate apparatus are similar but not identical to the receptors in the autonomic ganglia (Table 7-1). Both types respond to acetylcholine and nicotine. (However, as noted in Chapter 8, the receptors differ in their structural requirements for nicotinic blocking drugs.) When a nicotinic agonist is applied directly (by iontophoresis or by intra-arterial injection), an immediate depolarization of the end plate results, caused by an... 

Unlike iontophoresis, which acts on the transporting molecules and ions, US has been shown to act on the skin barrier itself The effects of sonophoresis depend on the "quality" of the barrier that is subject to US treatment thus, barriers which are intrinsically more permeable will be more liable to physical perturbation by US and vice versa. This may explain why the most successful attempts at the US-assisted extraction of glucose across the skin involved the use of a surfactant or chemical enhancer to better "normalize" the increased transport effects observed. One of the challenges in pretreatment-type sonophoresis is that the degree of skin permeability must be determined prior to drug placement. 

For current densities at or above 0.2mA/cm, the sensation associated with transdermal iontophoresis is determined by the type of ion being delivered into the skin. When human subjects compared the sensation experienced during iontophoresis of different salt solutions applied to the right and left forearms, delivery of calcium caused less sensation than delivery of phosphate, magnesium, and zinc, which caused less sensation than delivery of chloride, acetate, citrate, and sulfate, which in turn caused less sensation than delivery of lithium, potassium, and sodium. In general, multivalent ions were found to cause less sensation than monovalent ions. ... 

The skin permeation of ACV (Zovirax cream) applied as a finite dose was promoted to a greater extent as the duration of brush treatment was extended (Fig. 5.2). A significant increase in ACV transport was observed following brush treatment (p < 0.05). The use of iontophoresis proved generally less effective than employing the rotating brush in enhancing permeation. For example the effect of 10-min anodal iontophoresis on the skin permeation of ACV proved to be comparable to that obtained after application of brush treatment at SOON m" for 10s (Table 5.2). The iontophoretic method in this study employed optimum conditions (electrode type, anode pFl of buffer, 7.4 current intensity. 

Bradley I take your point. One does occasionally find a cell which is not spontaneously active but which appears, as it were, when ACh is injected. It is very difficult to study cells of this kind because you do not know whether it is still there when the iontophoresis is stopped. We can say, however, that the initial firing rate does not determine the type of response which is seen. 

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