Issues

JGP study shows that Kv12-encoded K⁺ currents reduce the repetitive firing rates of SCN neurons at night, thereby regulating daily oscillations in the master circadian pacemaker.

By describing the analogies and differences of a simple homologous circuit involving electrical synapses—the simplest form of synaptic communication—in two closely related species, this article demonstrates how we must be wary of cross-species generalizations.

Dapino et al. performed a comparative study of the mesencephalic trigeminal (MesV) nucleus from rats and mice, exposing species-specific differences in the operation of electrical synapses. Despite similar coupling strength, postsynaptic recruitment in rats is more efficient than in mice due to differential expression of the D-type K⁺ current.

In this study, Bonezzi et al. characterize the photoresponsivity of retinal cells during the development of light- and dark-reared mice. They find that retinal photoreceptors are responsive at postnatal day 8 (P8), second-order cells transmit photoreceptor input at P9, and that light shapes the maturation of photoreceptor signaling pathways.

Our current comprehensive structural and functional study validates the use of liquid nitrogen–frozen and cryostored porcine myocardium as an excellent test bed for biophysical studies of cardiac muscle that may lead to more consistent experiment results requiring reduced numbers of animals.

Lesage et al. identified multiple phosphorylation sites on the iFGF13 protein in adult mouse left ventricular Na_V1.5 channel complexes. Although manipulating these phosphosites did not affect the expression or gating properties of myocardial Na_V channels, they found differential iFGF13-dependent regulation of neonatal and adult ventricular Na_V channels.

Kriegeskorte et al. show that activation of the sodium channel subtypes Na_v1.3, Na_v1.5, Na_v1.6, and Na_v1.7, and two pain-linked mutations is alleviated by increasing temperature. Cooler temperatures, on the other hand, strongly enhance persistent currents of Na_v1.3. The impaired fast inactivation of the pain-linked Na_v1.7/I1461T mutation is further impaired by cooling, mimicking clinical findings.

Thoreson and Chhunchha use photomodulation and activity recordings to show that EAAT5 glutamate transporters can rapidly bind glutamate with micromolar affinity in mouse rods. This study establishes that, besides generating anion currents that shape voltage response, EAAT5 can actively participate in glutamate recycling at rod synapses.

Neurons in the suprachiasmatic nucleus, the master circadian pacemaker in mammals, display day–night oscillations in firing rates that drive daily rhythms in physiology and behavior. Here, we show that these oscillations are driven by day–night differences in subthreshold Kv12-encoded K⁺ currents.

In this work, Garcia et al. present a thermodynamically consistent model for ATP production in mitochondria, in which reaction rate constants are set such that detailed balance is satisfied. Simulations revealed that ATP production, but not its export, is the limiting step, and simulations with 3-D mitochondrial reconstructions linked the ATP production rate in the cytosol with morphological features of the organelles.