Dopamine D1 receptors regulate the light dependent development of retinal synaptic responses.

Retinal synaptic connections and function are developmentally regulated. Retinal synaptic activity plays critical roles in the development of retinal synaptic circuitry. Dopamine receptors have been thought to play important roles in the activity-dependent synaptic plasticity in central nervous system.

Endurance exercise training normalizes repolarization and calcium-handling abnormalities, preventing ventricular fibrillation in a model of sudden cardiac death.

The risk of sudden cardiac death is increased following myocardial infarction. Exercise training reduces arrhythmia susceptibility, but the mechanism is unknown. We used a canine model of sudden cardiac death (healed infarction, with ventricular tachyarrhythmias induced by an exercise plus ischemia test, VF+); we previously reported that endurance exercise training was antiarrhythmic in this model (Billman GE.

Prolonged Action Potential and After depolarizations Are Not due to Changes in Potassium Currents in NOS3 Knockout Ventricular Myocytes.

Ventricular myocytes deficient in endothelial nitric oxide synthase (NOS3(-/-)) exhibit prolonged action potential (AP) duration and enhanced spontaneous activity (early and delayed afterdepolarizations) during β-adrenergic (β-AR) stimulation. Studies have shown that nitric oxide is able to regulate various K(+) channels. Our objective was to examine if NOS3(-/-) myocytes had altered K(+) currents.

Activation of the basolateral membrane Cl- conductance essential for electrogenic K+ secretion suppresses electrogenic Cl- secretion.

Adrenaline activates transient Cl(-) secretion and sustained K(+) secretion across isolated distal colonic mucosa of guinea-pigs. The Ca(2+)-activated Cl(-) channel inhibitor CaCCinh-A01 (30 μm) significantly reduced electrogenic K(+) secretion, detected as short-circuit current (I(sc)). This inhibition supported the cell model for K(+) secretion in which basolateral membrane Cl(-) channels provide an exit pathway for Cl(-) entering the cell via Na(+)-K(+)-2Cl(-) cotransporters.

Light-evoked synaptic activity of retinal ganglion and amacrine cells is regulated in developing mouse retina.

Recent studies have shown a continued maturation of visual responsiveness and synaptic activity of retina after eye opening, including the size of receptive fields of retinal ganglion cells (RGCs), light-evoked synaptic output of RGCs, bipolar cell spontaneous synaptic inputs to RGCs, and the synaptic connections between RGCs and ON and OFF bipolar cells. Light deprivation retarded some of these age-dependent changes. However, many other functional and morphological features of RGCs are not sensitive to visual experience.

Cyclic nucleotide-gated ion channels in rod photoreceptors are protected from retinoid inhibition.

In vertebrate rods, photoisomerization of the 11-cis retinal chromophore of rhodopsin to the all-trans conformation initiates a biochemical cascade that closes cGMP-gated channels and hyperpolarizes the cell. All-trans retinal is reduced to retinol and then removed to the pigment epithelium. The pigment epithelium supplies fresh 11-cis retinal to regenerate rhodopsin.

[Research on the protein C-activating property and influencial factors of protein C activator isolated from the venom of Agkistrodon halys].

Objective: To investigate the protein C-activating property and experimental conditions that may affect the activities of protein C activator (PCA-SV).

Methods: PCA-SV's functional characteristic, possible anticoagulant and amidase activities were measured by method of APTT and that of specific chromogenic substrate respectively in various experimental conditions.

Results: PCA-SV can specifically act on protein C.

[Effect of fractions isolated from Naja naja atra venom on antioxidation in animals].

Objective: To study the antioxidation of fraction F and H isolated from Naja naja atra venom on homogenate and RBC autoxidation. And to explore the effect of two fractions on the activities of antioxidation enzymes in mice.

Method: Samples of tissues homogenates and RBC suspension were pretreated with fraction F/H, and then their generation of malondialdehyde(MDA) was examined.