The role of reverse mode of Naplus/Ca2plus exchanger in vascular response to acute hyponatremia

• Autorzy: Klapczynska K. , Kozniewska E.
• Języki publikacji: EN

Abstrakty

EN

In a previous study we have found that dilation of the middle cerebral artery (MCA) of the rat during acute hyponatremia depends on endothelium and NO/cGMP signalling. The production of NO in the endothelium is stimulated by the increase of intracellular concentration of Ca2+ which can occur either as a result of the release of calcium ions from intracellular stores or their infl ux from the extracellular space. The latter requires opening of specifi c Ca2+ channels of the cell membrane and/or operation of Na+ /Ca2+ exchanger (NCX) in the reverse mode. In the present study we sought the participation of the reverse mode of NCX in the response of MCA to acute hyponatremia. Experiments were performed on MCAs harvested from the brains of male Wistar rats and mounted in the organ chamber under the inverted microscope equipped with video camera and monitor. The diameter of the vessel was measured directly from the screen and recorded. The vessel was perfused at a transmural pressure of 80 mm Hg, temperature of 37°C and pH 7.4. Hyponatremia was induced by decreasing the intra- and extraluminal concentration of Na+ from 144 to 120 mM. In some experiments hyponatremia was preceded by the administration to the chamber of the inhibitor of the reverse mode of NCX (KB-R7943, 10 microM) or the inhibitor of L-type Ca2+ channel (Nimodipine, 0.1 microM). In the last experiment endothelium was removed before administration of KB-R7943 (10 microM) and lowering of Na+ . Hyponatremia resulted in the dilation of the MCA by 17% (P<0.05). This response was abolished by the pretreatment with KB-R7943 but not with Nimodipine. The results show that small decrease in the concentration of extracellular Na+ may stimulate reverse mode of NCX in the endothelium but not in the smooth muscle cells.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2009
• Tom: 69
• Numer: 1
• Opis fizyczny: p.99

Twórcy

autor

Klapczynska K.

• Laboratory of Experimental Neurosurgery, Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland

autor

Kozniewska E.

• Laboratory of Experimental Neurosurgery, Department of Neurosurgery, Mossakowski Medical Research Centre, Polish Academy of Sciences, Warsaw, Poland