The Change in the Electrical Resistance of the Scala Media Produced by Vasopressin

Abstract

The electrical resistance of the scala media (Rm) in the basal turn of the guinea pig was measured during perilymphatic perfusion with vasopressin. As the endocochlear potential (EP) diminished under the influence of vasopressin (0.1 mM), so the Rm increased. The Rm decreased when the EP decreased by vasopressin recovered above the pre-asphyctic level after the termination of temporary asphyxia. The present study demonstrates that the EP decrease produced by vasopressin is associated with the increase in Rm.

Change in K+Activity of the Scala Media Produced by Vasopressin

“…However, the difference in the re sponse of the EP to asphyxia between vaso pressin and furosemide [2,6] suggests that vasopressin changes the EP via another mechanism than furosemide.…”

“…Second, vasopressin changes the permeabil ity of the cochlear duct to K+, resulting in decrease in K+ concentration and EP. Mori et al [2] have shown that vasopressin pro duced an increase in the electrical resistance of the scala media corresponding closely to the change in EP. This refutes the EP de crease induced by vasopressin being due to breaks in the electrical insulation of the scala media resulting from the increase in the per meability of the cochlear duct to the electro lytes and favors the First possibility.…”

“…Our previous study reported that peri lymphatic perfusion with vasopressin, known as antidiuretic hormone, produced a reversible depression of the endocochlear potential (EP) [1], In a subsequent study we reported that the perilymphatic perfusion with vasopressin produced an increase in the electrical resistance of the scala media con comitant with a decrease in EP and that the change in the electrical resistance corre sponded closely to the change in EP [2], However, the mechanism underlying the de crease in EP induced by vasopressin is still unknown. In order to examine how vaso pressin acts on K+ transport in the cochlea, we measured the change in EP and K+ activ ity of the scala media simultaneously by means of double-barreled K+-sensitive mi croelectrodes during perilymphatic perfu sion with vasopressin.…”

Changes in P2Y4 receptor expression in rat cochlear outer sulcus cells during development

“…Variations in the intensities and durations of acoustic stimuli would cause fluctuations in endolymph cation composition in the absence of the regulation of rates of secretion and/or absorption. Ionic homeostasis in endolymph is known to be under the control of several extracellular hormones (Mori et al, 1987;Pitovski et al, 1993;Wangemann et al, 2000), including purinergic receptors (Järlebark et al, 2000;Marcus et al, 2005).…”