Cell Volume Changes and Taurine Release in Cerebral Cortical Slices

Taurine release and swelling of cerebral cortex slices from adult and developing mice in media of different ionic compositions

“…The results do not indicate this to be the case. In developing mice, in which the responses to depolarizing K + concentrations are severalfold larger than in adult mice (Kontro and Oja, 1987a;Oja and Kontro, 1989; the present study), the results on slices bore generally more resemblance to results reported on cultured cells Schousboe, 1988, 1989;Schousboe et al, 1990;Oja and Saransaari, 1992). It should be kept in mind that both neurons and astrocytes used for cell culture are obtained from immature brain tissue and may not mature to the same degree as they do in the brain in situ.…”

“…However, in most experiments of ours the results with the impermeant anion gluconate on the release of taurine were the same as those with the permeant anion acetate in spite of the opposite effects of gluconate and acetate on intracellular swelling. Furthermore, our experiments on cultured cells have yielded results with acetate similar to those with gluconate as the substitute of chloride (Oja and Saransaari, 1992). Also, in rat cerebral cortex slices there has been no significant difference among the effects of propionate, isethionate, gluconate, or methylsulphate on the release of GABA, 5-hydroxytryptamine, or norepinephrine (Turner et al, 1987).…”

“…High concentrations of Kf in medium have been shown to cause swelling of astrocytes in culture (Walz and Hinks, 1985;Walz, 1987), which is accompanied by accumulation of K + (Kimelberg and Frangakis, 1986) and release of taurine (Pasantes-Morales and Schousboe, 1988. In cultured astrocytes the K t -evoked release of astrocytes can be completely blocked by hyperosmolarity or in media in which the ionic product of K + X C1-is kept constant in order to prevent cell swelling (Pasantes-Morales and Martin et al, 1990;Oja and Saransaari, 1992). C1-ions seem to be essential for swelling and release of taurine in astrocytes, since both processes are inhibited in low-CI-media or in the presence of furosemide (Kimelberg and Frangakis, 1985;Pasantes-Morales et al, 1990;Oja and Saransaari, 1992).…”

“…In cultured astrocytes the K t -evoked release of astrocytes can be completely blocked by hyperosmolarity or in media in which the ionic product of K + X C1-is kept constant in order to prevent cell swelling (Pasantes-Morales and Martin et al, 1990;Oja and Saransaari, 1992). C1-ions seem to be essential for swelling and release of taurine in astrocytes, since both processes are inhibited in low-CI-media or in the presence of furosemide (Kimelberg and Frangakis, 1985;Pasantes-Morales et al, 1990;Oja and Saransaari, 1992). On the other hand, swelling of astrocytes causes depolarization of their membranes proportionally to the degree of swelling (Kimelberg and O'Connor, 1988).…”

Handbook of Neurochemistry and Molecular Neurobiology

“…Release of preloaded labeled taurine evoked by depolarizing concentrations of K þ has been demonstrated in many neuronal preparations from the CNS (Kontro, 1979;Kontro and Oja, 1987b;Holopainen and Kontro, 1989;Oja et al, 1990a;Rogers et al, 1991;Oja and Saransaari, 1995;Zheng et al, 2000;Saransaari and Oja, 2006). However, when cell swelling is prevented, K þ stimulation fails to evoke any release from astrocytes (Pasantes-Morales and Pasantes-Morales et al, 1990;Oja and Saransaari, 1992). The chemical identity of the released taurine has been confirmed by showing that potassium stimulation evokes release of endogenous taurine in brain tissue both in vitro and in vivo (Oja and Kontro, 1989;Sved and Curtis, 1993;Oja and Saransaari, 1995;Böckelmann et al, 1998;Colivicchi et al, 1998;Saransaari and Oja, 1998b;Estevez et al, 2000;Molchanova et al, 2004a).…”