Hyperosmolarity-induced hyperpolarization of the membrane potential of the retinal pigment epithelium

Mukoh, S; Kawasaki, Kazuo; Yonemura, D; Tanabe, J

doi:10.1007/bf00158926

Cited by 8 publications

(9 citation statements)

References 8 publications

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“…The intravenous infusion of either a hyperosmotic agent or acetazolamide causes a hyperpolarization of the basal RPE membrane and a fall in the standing potential [24,25]. These responses do not depend on retina at all and can be elicited in isolated RPE-choroid preparations.…”

Section: Basic Electrical Responses Of the Rpementioning

confidence: 94%

Clinical electrophysiology of the retinal pigment epithelium

Marmor

1991

Doc Ophthalmol

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There is no ideal electrophysiological test for retinal pigment epithelial (RPE) function. The light-induced responses (EOG, c-wave, fast oscillation) that require photoreception are not pure RPE signals, and even the widely-used EOG has not been associated with any specific physiological disturbance of the RPE or retina. The discovery of non-photic RPE responses (hyperosmolarity, acetazolamide and bicarbonate) has enhanced the possibility of finding tissue-specific RPE tests, but these responses have yet to be correlated with specific RPE functional activity or pathology. We may face a dilemma in our search for RPE tests, insofar as electrophysiology measures membrane changes, but RPE membrane activity is related only indirectly to many functions of the RPE cell. These concerns notwithstanding, RPE electrophysiology can be a valuable clinical tool if one accounts for the physiological limitations and assets of the procedures.

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Section: Basic Electrical Responses Of the Rpementioning

confidence: 94%

Clinical electrophysiology of the retinal pigment epithelium

Marmor

1991

Doc Ophthalmol

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“…Accumulation of its metabolite lactic acid leads to lactic acidosis. Serious side effect like hyperosmolality is reported in burn pediatric patients treated with topical silver sulfadiazine containing PG and irreversible precipitation deafness was reported in premature neonates administered with multivitamin products having PG (Mukoh et al 1985). Other toxic effects associated with oral and parenteral PG includes hemolysis, seizures, respiratory depression and hypertension.…”

Section: Propylene Glycolmentioning

confidence: 97%

Excipients in Pediatric Formulations: Biopharmaceutical and Toxicological Considerations

Vangara¹,

Yellepeddi

2015

Excipient Applications in Formulation Design and Drug Delivery

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Excipients are commonly used in pharmaceutical formulations for a variety of applications such as solubility and stability enhancement, taste-masking, tablet compaction, etc. Excipients are also used in the preparation of pediatric formulations for purposes similar to that of adult formulations. However, excipients that are used in adult formulations may not be suitable for the development of formulations for pediatric use due to toxicity concerns. Toxicity of excipients in pediatric populations is mainly due to rapid developmental changes, slower metabolism and elimination, and varied organ and body composition. For example, solvents such as ethanol and propylene glycol that are commonly used in pediatric formulations as solubility enhancers, showed life-threatening adverse events. Therefore, it is apparent that the use of excipients in pediatric formulations requires additional risk assessment by practitioners to avoid potential toxicity issues. Regulatory agencies in the United States of America and Europe are working together to create and maintain a database of Safety and Toxicity of Excipients for Pediatrics (STEP). The purpose of this book chapter is to review the role of excipients and their toxicity in pediatric formulations along with strategies to mitigate the potential risks of toxicity associated with their use in pediatric patients.

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“…In addition, hyperosmolar stress of the RPE induced an increase in the ocular standing potential (positive wave) (Yamada et al, 1987). Furthermore, the apical and basolateral membrane potentials of frog RPE were simultaneously hyperpolarized by hyperosmotic stress applied at either the apical or basolateral side of the epithelia (Mukoh et al, 1985). When hyperosmolar stress is applied at the apical side of the epithelia, the apical membrane potential is greater than the basolateral membrane potential, with an increased transepithelial potential (Mukoh et al, 1985).…”

Section: Consequences Of Hyperosmolar Stress On the Retinal Pigmentedmentioning

confidence: 99%

“…Furthermore, the apical and basolateral membrane potentials of frog RPE were simultaneously hyperpolarized by hyperosmotic stress applied at either the apical or basolateral side of the epithelia (Mukoh et al, 1985). When hyperosmolar stress is applied at the apical side of the epithelia, the apical membrane potential is greater than the basolateral membrane potential, with an increased transepithelial potential (Mukoh et al, 1985). When hyperosmolar stress is applied at the basolateral side of the epithelia, it induces the hyperpolarization of the basolateral membrane potential, and simultaneously of the apical membrane potential to a lesser extent, thereby resulting in a reduction in transepithelial potential (Mukoh et al, 1985).…”

Section: Consequences Of Hyperosmolar Stress On the Retinal Pigmentedmentioning

confidence: 99%

“…When hyperosmolar stress is applied at the apical side of the epithelia, the apical membrane potential is greater than the basolateral membrane potential, with an increased transepithelial potential (Mukoh et al, 1985). When hyperosmolar stress is applied at the basolateral side of the epithelia, it induces the hyperpolarization of the basolateral membrane potential, and simultaneously of the apical membrane potential to a lesser extent, thereby resulting in a reduction in transepithelial potential (Mukoh et al, 1985). In chick RPE, retinal hyperosmotic stress depolarized the basolateral membrane and increased the amplitude of the light-evoked c-wave of the electroretinogram, decreased basolateral membrane resistance and RPE membrane polarization during the c-wave (Shirao and Steinberg, 1987).…”

Section: Consequences Of Hyperosmolar Stress On the Retinal Pigmentedmentioning

confidence: 99%

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Origins and consequences of hyperosmolar stress in retinal pigmented epithelial cells

et al. 2014

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The retinal pigmented epithelium (RPE) is composed of retinal pigmented epithelial cells joined by tight junctions and represents the outer blood-retinal barrier (BRB). The inner BRB is made of endothelial cells joined by tight junctions and glial extensions surrounding all the retinal blood vessels. One of the functions of the RPE is to maintain an osmotic transepithelial gradient created by ionic pumps and channels, avoiding paracellular flux. Under such physiological conditions, transcellular water movement follows the osmotic gradient and flows normally from the retina to the choroid through the RPE. Several diseases, such as diabetic retinopathy, are characterized by the BRB breakdown leading to leakage of solutes, proteins, and fluid from the retina and the choroid. The prevailing hypothesis explaining macular edema formation during diabetic retinopathy incriminates the inner BRB breakdown resulting in increased osmotic pressure leading in turn to massive water accumulation that can affect vision. Under these conditions, it has been hypothesized that RPE is likely to be exposed to hyperosmolar stress at its apical side. This review summarizes the origins and consequences of osmotic stress in the RPE. Ongoing and further research advances will clarify the mechanisms, at the molecular level, involved in the response of the RPE to osmotic stress and delineate potential novel therapeutic targets and tools.

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Hyperosmolarity-induced hyperpolarization of the membrane potential of the retinal pigment epithelium

Cited by 8 publications

References 8 publications

Clinical electrophysiology of the retinal pigment epithelium

Clinical electrophysiology of the retinal pigment epithelium

Excipients in Pediatric Formulations: Biopharmaceutical and Toxicological Considerations

Origins and consequences of hyperosmolar stress in retinal pigmented epithelial cells

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