Assuntos
Aminobutiratos/farmacologia , Membrana Celular/efeitos dos fármacos , Condutividade Elétrica/efeitos dos fármacos , Imidazóis/farmacologia , Músculos/efeitos dos fármacos , Nephropidae , Ácido gama-Aminobutírico/farmacologia , Acetatos/administração & dosagem , Acetatos/farmacologia , Animais , Relação Dose-Resposta a Droga , Interações Medicamentosas , Imidazóis/administração & dosagem , Músculos/citologia , Picrotoxina/farmacologia , Receptores de Droga , Estimulação Química , Ácido gama-Aminobutírico/administração & dosagemAssuntos
Alcaloides/farmacologia , Aminobutiratos/antagonistas & inibidores , Encéfalo/efeitos dos fármacos , Estimulantes do Sistema Nervoso Central/farmacologia , Medula Espinal/efeitos dos fármacos , Aminobutiratos/administração & dosagem , Aminobutiratos/farmacologia , Animais , Anuros , Gatos , Relação Dose-Resposta a Droga , Antagonismo de Drogas , Éteres Cíclicos/farmacologia , Nephropidae , Junção Neuromuscular/efeitos dos fármacos , Picrotoxina/farmacologia , Receptores de Droga/efeitos dos fármacos , Compostos de Espiro/farmacologiaRESUMO
1. The ;local vesicle population', namely the population of synaptic vesicles lying within a zone 0.25 mum wide adjacent to the presynaptic membrane and expressed as ;vesicles mum(-2)' has been estimated in rat superior cervical ganglia maintained in vitro for 1 h. Ganglia were either unstimulated or stimulated tetanically during the last few minutes of the in vitro period.2. Individual local vesicle populations at synapses in groups of ganglia which had received the same treatment showed an approximately normal frequency distribution.3. The technique of stimulation did not permit fixation during tetanus, but the mean local vesicle population in ganglia fixed a few seconds after 10 Hz tetani of up to 10 min duration were significantly (P < 0.001) higher than the unstimulated control value of 124.0 +/- S.E. 3.2. Ganglia fixed a few seconds after 3 min tetani at 10 Hz had a mean local vesicle population of 155.7 +/- S.E. 5.7, rising slightly but not significantly to 165.0 +/- S.E. 4.3 at 1 min and 163.1 +/- S.E. 5.2 at 2 min after tetanus. Thereafter the mean local vesicle population fell slowly, reaching control level between 10 and 20 min after tetanus.4. In terms of the vesicle hypothesis, the observations suggest that post-tetanic potentiation might arise from a closer clustering of vesicles about release areas resulting in an increase in fractional release. It is suggested that stimulation increased the local vesicle population by promoting vesicle mobilization rather than by altering the size or shape of the presynaptic terminals. The ;mobilizing agent' might be intracellular Ca(2+).5. The results appear to be consistent with those of other workers where experimental conditions and the region in which vesicles were counted were comparable.6. Alternative interpretations for the findings, not involving the vesicle hypothesis, are considered.
Assuntos
Fibras Autônomas Pré-Ganglionares/fisiologia , Gânglios Autônomos/fisiologia , Vesículas Sinápticas/fisiologia , Potenciais de Ação , Animais , Contagem de Células , Estimulação Elétrica , Feminino , Técnicas In Vitro , Masculino , Microscopia Eletrônica , Ratos , Transmissão SinápticaAssuntos
Gânglios Autônomos/citologia , Transmissão Sináptica , Vesículas Sinápticas/efeitos dos fármacos , Potenciais de Ação , Animais , Cafeína/farmacologia , Cálcio/farmacologia , Estimulação Elétrica , Epinefrina/farmacologia , Gânglios Espinais/efeitos dos fármacos , Gânglios Espinais/fisiologia , Técnicas In Vitro , Magnésio/farmacologia , Microscopia Eletrônica , Morfina/farmacologia , Ratos , Membranas Sinápticas , Vesículas Sinápticas/fisiologiaRESUMO
1. In four out of seven experiments, prostaglandin-like activity was detected in prevertebral venous blood from the superior cervical ganglion, collected during and after preganglionic nerve stimulation.2. Prostaglandins E(1), E(2), F(2alpha) and a prostaglandin A were identified using solvent partition, column and thin-layer chromatography and bioassay techniques.3. The release of PGF(2alpha) was confirmed by combined gas chromatography-mass spectrometry.
