Sodium nitroprusside alters dark voltage and light responses in isolated retinal rods during whole-cell recording
| Autor: | Karl-Friedrich Schmidt, Yoshihiko Yamamoto, Gottfried N. Nöll |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
Nitroprusside
IBMX Light GTP' Physiology Rana temporaria Dark Adaptation Nitric Oxide Membrane Potentials chemistry.chemical_compound medicine Animals Photoreceptor Cells Patch clamp Rana esculenta Phosphodiesterase Depolarization Hyperpolarization (biology) Sensory Systems Electrophysiology Enzyme Activation EGTA chemistry Biochemistry Guanylate Cyclase Biophysics Guanosine Triphosphate Sodium nitroprusside medicine.drug |
| Zdroj: | Visual Neuroscience. 9:205-209 |
| ISSN: | 1469-8714 0952-5238 |
| DOI: | 10.1017/s0952523800009664 |
| Popis: | Dark voltage and light responses of isolated retinal rods ofRana esculentawere investigated by employing the whole-cell patch-clamp technique. When the recording pipette was filled with a medium devoid of nucleotides, a spontaneous hyperpolarization of the dark voltage partly due to a diffusional loss of cGMP and its precursor GTP and a retardation in the recovery of the light responses was observed. The larger part of the retardation of the light responses was prevented by 1 mM ATP. Addition of GTP attenuated the hyperpolarization, but did not abolish it completely. When the nitric-oxide-releasing substance sodium nitroprusside plus GTP was applied, the tendency of hyperpolarization disappeared and a stable dark voltage or even a slight depolarization was measured during the whole-cell recording period. Similar results were also obtained when GTP was given in combination with either EGTA or IBMX which are both known to interfere with the cGMP regulating enzymes in retinal rods. In addition to its effects on the dark voltage, an acceleration of the recovery phase of the light responses by sodium nitroprusside was also observed. Our observations strongly suggest that sodium nitroprusside activates guanylate cyclase in photoreceptors, as it does in other tissues, but we cannot exclude with certainty an effect on the phosphodiesterase. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|