| 1. |
- Perez, M T, et al.
(författare)
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Colocalization of (3H)-adenosine accumulation and GABA immunoreactivity in the chicken and rabbit retinas
- 1987
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Ingår i: Histochemistry. - 0301-5564. ; 87:5, s. 7-413
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Tidskriftsartikel (refereegranskat)abstract
- Using combined autoradiography and immunohistochemistry, we have compared (3H)-adenosine accumulation and GABA immunoreactivity in the chicken and rabbit retinas. Colocalization of the two markers was observed in a subset of amacrine cells and in certain cell bodies in the ganglion cell layer in both species and in a few horizontal cells in the chicken retina. Cells that contained only (3H)-adenosine or GABA were also seen. The degree of colocalization differed greatly between the two species. The results demonstrate a morphological relationship between the adenosine and GABA systems and provides information on the possible anatomical substrates underlying at least some types of functional interactions.
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| 2. |
- Perez, M T, et al.
(författare)
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Release of endogenous and radioactive purines from the rabbit retina
- 1986
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Ingår i: Brain Research. - : Elsevier BV. - 0006-8993. ; 398:1, s. 12-106
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Tidskriftsartikel (refereegranskat)abstract
- The adenine nucleotide pool of rabbit retina was labeled by an intravitreal injection in vivo of [3H]adenosine. Practically all the radioactivity was retained in the form of adenine nucleotides. The relative proportion of [3H]adenine nucleotides was the same as that of endogenous nucleotides. Potassium depolarization (43.6 mM) in vitro caused a rapid increase in the rate of release of radioactive purines. The radioactive material was composed of hypoxanthine, xanthine, inosine and trace amounts of adenine, adenosine and adenine nucleotides. The release of radioactive purines was delayed and reduced by the addition of the nucleoside inhibitor dipyridamole suggesting that the purines may be released in the form of nucleosides. Similarly, the addition of the ecto 5'-nucleotidase inhibitor alpha, beta-methylene ADP (AOPCP) did not alter the release of radioactivity or the composition of the released purines. Endogenous hypoxanthine, xanthine and inosine could be detected in the effluents, but there was only a very modest increase following potassium depolarization. There was a slight, but significant, decrease in the release of endogenous adenosine and increase in AMP after AOPCP. It is concluded that there is an intensive uptake and phosphorylation of adenosine in the rabbit retina. Depolarization induces release of radioactive purine nucleosides and bases. Most of these compounds appear to be released as such, but in addition there may be a small (maximally a few per cent of the total) fraction of the purines that are released as nucleotides.
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| 3. |
- Perez, M T, et al.
(författare)
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Stimulation-evoked release of purines from the rabbit retina
- 1988
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Ingår i: Neurochemistry International. - : Elsevier BV. - 0197-0186. ; 13:3, s. 18-307
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Tidskriftsartikel (refereegranskat)abstract
- The evoked release of purines from rabbit retinae preloaded with [(3)H]adenosine was studied in vitro. Potassium (8.6-43.6 mM) and ouabain (1 or 10 microM) increased the release of radioactivity in a concentration-dependent manner. The K(+)-evoked release was significantly reduced when the superfusion was carried out at 2-4 degrees C. The effect of K(+) (8.6, 13.6 and 23.6 mM) and of ouabain (1 microM) were completely abolished when the retinae were superfused with a Ca(2+)-free medium containing 0.1 mM EGTA. Calcium removal only partially reduced the effect of higher K(+) and ouabain concentrations (43.6 mM and 10 microM, respectively). Further, the effect of K(+) was found to be independent of extracellular Ca(2+) when retinae were pretreated with ouabain for 30 min. Stimulation of the retina with light flashes induced a small, persistent increase in the release of radioactivity observable for several minutes after the end of stimulation. The superfusate contained mainly hypoxanthine and inosine. There were no significant changes in the relative proportions of the different purine compounds released before or in response to either K(+) (23.6 mM) or ouabain (10 microM) stimulation. Potassium stimulation significantly increased the release of adenosine, inosine and hypoxanthine. Addition of the adenosine deaminase inhibitor, erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA), significantly increased the relative proportions of released endogenous adenosine and inosine. The results indicate that K(+) stimulation induces the release of purines from the rabbit retina by a Ca(2+)- and energy-dependent process. Light flashes also induce a purine release. The results suggest an active role for adenosine in retinal neurotransmission.
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