Dimethyl sulfoxide elevates intracellular Ca2+ and mimics effects of increased light intensity in a photoreceptor.
A 1% (v/v) solution of dimethyl sulfoxide (DMSO) added to the saline bath of isolated Balanus eburneus photoreceptors increased receptor potential amplitude by 40-50% and shortened time to peak amplitude and latency by 20-25%. The light-sensitive membrane current of voltage-clamped cells was increased systematically as DMSO concentration was increased from 1% to 10%. The null potential of the light sensitive current was unaffected by DMSO with short pulses of light, indicating that DMSO has no direct effect on ion selectivity of the light-sensitive channel. Absorbance changes of cell injected with the calcium indicator arsenazo III show that DMSO elevates intracellular Ca2+ (Cai). Current-voltage relations in darkness reveal that DMSO induces a small sustained inward current (approximately 5 nA) which has a null potential similar to the light-induced current. DMSO may activate the light-sensitive conductance via the increase in Cai. However, the altered kinetics and increased amplitude of the receptor current are opposite to the desensitizing effects normally observed with increased Cai.
Brown
H M
HM
Department of Physiology, University of Utah, Salt Lake City 84108.
Rydqvist
B
B
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D004594:Electrophysiology; D066298:In Vitro Techniques; D010786:Photoreceptor Cells / Q000187:drug effects* / Q000502:physiology; D015290:Second Messenger Systems / Q000187:drug effects*; D001468:Thoracica / Q000502:physiology*
D002118:Calcium; D004121:Dimethyl Sulfoxide