A duration-dependent negative potential in the cichlid electroretinogram.

A negative potential can be evoked in the local electroretinogram of the cichlid fish Cichlasoma octofasciatum by light stimuli of duration longer than 70 msec. This response superficially resembles the proximal negative response, but differs in some waveform components and dependence upon stimulus configuration and duration.     

Spectral distribution of the negative potential in the cichlid electroretinogram

Summary A negative potential occurring in the ERG of certain cichlid fishes shows a unique set of properties when evoked by monochromatic light. Spectral distributions determined forCichlasoma octofasciatum andHemichromis bimaculatus show a blue (460–478 nm) maximum, no Purkinje shift upon light adaptation, and secondary peaks correlated with the species' behavioral preferences in reproduction and parental care.     

Evidence for rapid speciation in African cichlid fishes

Summary Extremely rapid divergence among 7 species of African cichlid fishes is suggested by high estimates of allozymic similarity. Significant differences in gene frequencies among sympatric populations support reproductive isolation of these taxa.A portion of this study was submitted in partial fulfillment of requirments for the Ph. D from the State University of New York, Stony Brook. I thank T. D. Eccles and J. Tarbit for support and expertise, R. H. Gibbs, Jr, and V. G. Springer for review of an earlier draft, and R. K. Koehn for interest in all stages of this work. Supported in part by grants GM-25343 and GB-38662 from NIH and NSF (to RKK) and a grant-in-aid from the Society of Sigma Xi.     

Relation between the chick electroretinogram and body temperature

Zusammenfassung Untersuchung der Beziehung zwischen ERG und Körpertemperatur bei Küken ergab Abnahme derb-Wellen bei Verminderung der Rektaltemperatur, ohne Beeinflussung der Amplitude dera-Welle.     

Melatonin decreases the amplitude of the b-wave of the human electroretinogram

In a double-blind placebo crossover study of 13 healthy volunteers, the pineal hormone melatonin (10 mg) was given at 4 pm, and the electroretinogram measured under conditions of dark and light adaptation. A significant diminution of b-wave amplitude was found under both photopic (=5.4 V, p<0.05) and scotopic conditions (=7.4 V, p<0.01). These data indicate that melatonin may transduce the dark signal at the level of the retina as well as the pineal. Acute administration of melatonin decreases sensitivity to light.     

Effect of strychnine on the electroretinogram of the isolated rabbit retina

Zusammenfassung Strychnin in einer Konzentration von 3×10^–6 bis 3,5×10^–5 M/l verursacht eine vorübergehende Vergrösserung derb-Welle des ERG der isolierten Kaninchennetzhaut, in einer Konzentration von 7×10^–5 bis 7×10^–4 M/l verkleinert es dieb-Welle. Aus den Ergebnissen wird geschlossen, dass die Substanz zumindest teilweise schon auf die Schicht des zweiten Neurons wirkt.     

Action of carbaryl on the electroretinogram of the white mouse]

Carbaryl intoxication results in important modifications of the Mouse ERG, with an increase of the latency and a decrease of the amplitude, then a suppression of b-wave. This action is supposed to be provoked by the anticholinesterasic properties of carbamates, which result in a section of retinian synapses.     

The effect of aspartate on the electroretinogram of the vertebrate retina

Zusammenfassung Es wird gefunden, dass nach Applikation des zur Perfusionsflüssigkeit zugefügtenl-Aspartats auf die isolierte Froschretina eine auffallende Hemmung dera ₂- undb-Welle auftritt, dies jedoch ohne sichtbare Veränderung der Form und Amplitude des «early and late receptor potential».     

A negative inotropic effect of acetylcholine in the presence of several phosphodiesterase inhibitors

Summary The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine (IBMX) reveal a negative inotropic effect of acetylcholine in cat ventricular heart muscle. This effect is unrelated to -adrenoceptor stimulation and possibly mediated by the accumulation of cyclic GMP.I thank Mrs Petra Lauck for help. This work was supported by the Deutsche Forschungsgemeinschaft.     

A negative inotropic effect of acetylcholine in the presence of several phosphodiesterase inhibitors

The phosphodiesterase inhibitors papaverine, theophylline and 3-isobutyl-1-methylxanthine (IBMX) reveal a negative inotropic effect of acetylcholine in cat ventricular heart muscle. This effect in unrelated to beta-adrenoceptor stimulation and possibly mediated by the accumulation of cyclic GMP.     

A working hypothesis for negative ion generators

Summary The effects of negative ion generators may be explained by reactions of carbonate radical anion, or alternatively, by physical factors such as the electric field of the ions generated by these apparatuses.