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M Dóda

Publications and source records attributed to M Dóda.

40 records · Page 3Linked to original sources
PubMedDate not supplied

Effect of hypoxia and glucose deprivation on ATP level, adenylate energy charge and [Ca2+]o-dependent and independent release of [3H]dopamine in rat striatal slices.

Release of [3H]dopamine ([3H]DA) from rat striatal slices kept under hypoxic or/and glucose-free conditions was measured using a microvolume perfusion method. The corresponding changes in nucleotide content were determined by reverse-phase high-performance liquid chromatography (RPHPLC). The resting release of [3H]DA was not affected by hypoxia, but under glucose-free conditions massive [Ca2+]o-independent release of [3H]DA was observed. Hypoxia reduced the energy charge (E.C.) and the total purine content from 19.36 +/- 4.15 to 6.98 +/- 1.83 nmol/mg protein. Glucose deprivation by itself, or in combination with hypoxia, markedly reduced the levels of adenosine 5'-triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP). The E.C under glucose-free conditions was significantly reduced from 0.73 +/- 0.04 to 0.44 +/- 0.20. When the tissue was exposed to hypoxic and glucose-free conditions for 18 min the level of ATP was reduced to 3.15 +/- 0.11 nmol/mg protein. However, when the exposure time was 30 min the ATP level was further reduced to 1.11 +/- 0.37 nmol/mg protein. The resting release was enhanced in a [Ca2+]o-independent manner, but there was no release in response to stimulation, and tetrodotoxin did not affect the enhanced resting release, indicating that the release was not associated with axonal activity. Similarly, 50 microM ouabain, inhibitor of Na+/K(+)-activated ATPase, enhanced the release of [3H]DA at rest in a [Ca2+]o-independent manner. It seems very likely that the reduced ATP level under glucose-free conditions leads to an inhibition of the activity of Na+/K(+)-ATPase that results in reversal of the uptake processes and in [Ca2+]o-independent [3H]DA release from the axon terminals.

Adenine Nucleotides↗
PubMedDate not supplied

Dopaminergic inhibition of sympathetic activity in the cat.

The influence of dopaminergic agonists on the spontaneous and evoked activity of the sympathetic postganglionic renal efferent fibres was studied in lightly anaesthetized cats (urethane, 600 mg/kg, ip). Apomorphine, bromocriptine and piribedil (0.2, 0.07 and 0.4 mg/kg iv, respectively) depressed the spontaneous activity of the renal nerve. Electrical stimulation (16 V, 0.3 ms, 2-128 Hz, 2 s) of the sciatic nerve elicited a burst of activity of the sympathetic efferents followed by a silent period. Apomorphine and piribedil (the same doses as above) prolonged the duration of the silent periods. All these effects of dopaminergic agonists were antagonized by haloperidol (0.05-0.1 mg/kg iv). The results suggest that administration of dopaminergic agonists leads to preponderance of inhibition in the somato-sympathetic reflex integration.

Animals↗