SELECTIVE EFFECT OF A NEW ANTITUBERCULOUS DRUG, RIFAMPICIN, ON THE c‐WAVE OF THE SHEEP ELECTRORETINOGRAM

Self Cite

The present investigation shows that the membrane properties of the sheep pigment epithelial cells were very rapidly and severely affected by sodium iodate, whereas the effects concerning the neuroretina were delayed. The c-wave of the ERG was immediately abolished and replaced by a cornea-negative potential, but the a- and b-waves were preserved for about 80-100 min. Ultrastructurally the plasma membranes (particularly the basal plasma membrane) of the pigment epithelial cells were destroyed or less distinct than normally. The cell organelles were swollen and ruptured. There were indications that the pigment epithelium could no longer participate in the receptor outer segment turnover. The photoreceptor cells were morphologically undamaged, and few or no signs of injury were observed in the inner layers of the retina. The effects upon the neuroretinal functions seen after 80-100 min, consisting of a reduction of alpha- and beta-wave amplitudes, were most likely caused by an inability of the pigment epithelium to maintain in the long run its metabolic and barrier properties. It appears that at an early stage after sodium iodate injection, the present preparation may be useful for the study of the effects on the neuroretina proper of drugs and other agents.

Section: Discussionsupporting

confidence: 83%

CHANGES IN ULTRASTRUCTURE AND FUNCTION OF THE SHEEP PIGMENT EPITHELIUM AND RETINA INDUCED BY SODIUM IODATE¹

Nilsson

Knave

Persson

1977

Self Cite

“…This was initially remarkable, but decreased with time. This finding is in accordance with earlier observations in sheep (Knave et al 1973;Calissendorff et al 1974) and man (Skoog & Nilsson 1974). In man, simultaneous recording shows that there is a covariation of the c-wave and standing potential oscillations (Nilsson & Skoog 1975).…”

Section: Discussionsupporting

confidence: 93%

Some problems involved in employing the ERG c‐wave in pharmacological experiments: conditioning in pigmented rabbits

Nao‐i

Kim

Honda

1985

The large inter- and intra-individual variations in ERG c-waves have prevented the application of the component in pharmacological experiments on the retinal pigment epithelial function. We examined some of the problems involved in employing the c-wave in pharmacological experiments using rabbit retinas. 1) Under our experimental conditions, the c-wave amplitudes in some rabbits reached equilibrium under intermittent stimuli, while in others they increased with time and did not reach a constant level in 3 h. 2) The c-wave amplitudes of the right and left eyes were similar, indicating that the contralateral eye can be used as a control during local administration of drugs. 3) The c-wave amplitude under 50 lux light had smaller inter-individual variations than that in the dark. This may be a useful indicator of the retinal pigment epithelium function when drugs are administered systemically.

“…The c-wave has been found to be sensitive to a number of substances, e.g. adrenaline (Therman 1937), sodium azide and sodium iodate (Noel1 1954) and the antituberculous drug rifampicin (Knave, Persson, Calissendorff & Nilsson 1973). Recent experiments on sheep (Knave, Persson & Nilsson 1974 a) showed a large increase in c-wave amplitude after the intravenous injection of ethyl alcohol, which also influenced the standing potential (SP) of the eye.…”

Section: Discussionmentioning

confidence: 99%

THE c‐WAVE OF THE HUMAN D.C. REGISTERED ERG. III. EFFECTS OF ETHYL ALCOHOL ON THE c‐WAVE

Skoog

1974

The amplitude of the c-wave of the human d.c. registered ERG is known to oscillate with a frequency of about 2Jhour in response to repeated stimulations. A small oral dose of ethyl alcohol caused a marked increase in amplitude of the oscillations and also elevated their mean level. A first peak was reached 10-15 min after the intake of alcohol. The b-wave increased slightly in response to ethanol, but no significant effect on the a-wave was observed with the present doses and stimulus conditions. The results encourage further studies of drug influence on the c-wave with the intention of correlating ocular toxicity of a substance to c-wave changes.