Goldfish and crucian carp are natural models of anoxia tolerance in the retina.

Vertebrates need oxygen to survive. The central nervous system has an especially high energy demand, so brain and retinal neurons quickly die in anoxia. But fish of the genus Carassius are exceptionally anoxia-tolerant: the crucian carp (C.

Seasonal changes in membrane structure and excitability in retinal neurons of goldfish (Carassius auratus) under constant environmental conditions.

Seasonal modifications in the structure of cellular membranes occur as an adaptive measure to withstand exposure to prolonged environmental change. Little is known about whether such changes occur independently of external cues, such as photoperiod or temperature, or how they may impact the central nervous system. We compared membrane properties of neurons isolated from the retina of goldfish (Carassius auratus), an organism well adapted to extreme environmental change, during the summer and winter months.

The Opto-Respiratory Compromise: Balancing Oxygen Supply and Light Transmittance in the Retina.

The light-absorbing retina has an exceptionally high oxygen demand, which imposes two conflicting needs: high rates of blood perfusion and an unobstructed light path devoid of blood vessels. This review discusses mechanisms and physiological trade-offs underlying retinal oxygen supply in vertebrates and examines how these physiological systems supported the evolution of vision.

Mitochondrial KATP channels stabilize intracellular Ca2+ during hypoxia in retinal horizontal cells of goldfish (Carassius auratus).

Neurons of the retina require oxygen to survive. In hypoxia, neuronal ATP production is impaired, ATP-dependent ion pumping is reduced, transmembrane ion gradients are dysregulated, and intracellular Ca2+ concentration ([Ca2+]i) increases enough to trigger excitotoxic cell death. Central neurons of the common goldfish (Carassius auratus) are hypoxia tolerant, but little is known about how goldfish retinas withstand hypoxia.

Retinal horizontal cells of goldfish (Carassius auratus) display subtype-specific differences in spontaneous action potentials in situ.

Horizontal cells (HCs) are neurons of the outer retina, which provide inhibitory feedback onto photoreceptors and contribute to image processing. HCs in teleosts are classified into four subtypes (H1-H4), each having different roles: H1-H3 feed back onto different sets of cones, H4 feed back onto rods, and only H1 store and release the inhibitory neurotransmitter, γ-aminobutyric acid (GABA). Dissociated HCs exhibit spontaneous Ca -based action potentials (APs), yet it is unclear if APs occur in situ, or if all subtypes exhibit APs.

Spontaneous action potentials in retinal horizontal cells of goldfish () are dependent upon L-type Ca channels and ryanodine receptors.

Horizontal cells (HCs) are interneurons of the outer retina that undergo graded changes in membrane potential during the light response and provide feedback to photoreceptors. We characterized spontaneous Ca-based action potentials (APs) in isolated goldfish () HCs with electrophysiological and intracellular imaging techniques. Transient changes in intracellular Ca concentration ([Ca]) were observed with fura-2 and were abolished by removal of extracellular Ca or by inhibition of Ca channels by 50 µM Cd or 100 µM nifedipine.

Retinal metabolism: A comparative look at energetics in the retina.

The retina is part of the central nervous system, and shares the characteristically high metabolism of the brain. The high energy demand of the retina is normally matched with a large supply of metabolites. When supply does not equal demand (e.

Calcium dynamics and regulation in horizontal cells of the vertebrate retina: lessons from teleosts.

Horizontal cells (HCs) are inhibitory interneurons of the vertebrate retina. Unlike typical neurons, HCs are chronically depolarized in the dark, leading to a constant influx of Ca Therefore, mechanisms of Ca homeostasis in HCs must differ from neurons elsewhere in the central nervous system, which undergo excitotoxicity when they are chronically depolarized or stressed with Ca HCs are especially well characterized in teleost fish and have been used to unlock mysteries of the vertebrate retina for over one century. More recently, mammalian models of the retina have been increasingly informative for HC physiology.