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A set of core concepts ("big ideas") integral to the discipline of physiology are important for students to understand and demonstrate their capacity to apply. We found poor alignment of learning outcomes in programs with physiology majors (or equivalent) from 17 Australian universities and the 15 core concepts developed by a team in the United States. The objective of this project was to reach Australia-wide consensus on a set of core concepts for physiology, which can be embedded in curricula across Australian universities. A four-phase Delphi method was employed, starting with the assembling of a Task Force of physiology educators with extensive teaching and curriculum development expertise from 25 Australian universities. After two online meetings and a survey, the Task Force reached agreement on seven core concepts of physiology and their descriptors, which were then sent out to the physiology educator community across Australia for agreement. The seven core concepts and their associated descriptions were endorsed through this process (n = 138). In addition, embedding the core concepts across the curriculum was supported by both Task Force members (85.7%) and educators (82.1%). The seven adopted core concepts of human physiology were Cell Membrane, Cell-Cell Communication, Movement of Substances, Structure and Function, Homeostasis, Integration, and Physiological Adaptation. The core concepts were subsequently unpacked into themes and subthemes. If adopted, these core concepts will result in consistency across curricula in undergraduate physiology programs and allow for future benchmarking.

A task force of physiology educators from 25 Australian universities generated an Australia-wide consensus on seven core concepts for physiology curricula. One adopted core concept was "cell membrane," defined as "Cell membranes determine what substances enter or leave the cell and its organelles. They are essential for cell signaling, transport, and other cellular functions." This concept was unpacked by a team of 3 Australian physiology educators into 4 themes and 33 subthemes arranged in a hierarchical structure up to 5 levels deep. The four themes related to defining the cell membrane, cell membrane structure, transport across cell membranes, and cell membrane potentials. Subsequently, 22 physiology educators with a broad range of teaching experience reviewed and assessed the 37 themes and subthemes for importance for students to understand and the level of difficulty for students on a 5-point Likert scale. The majority (28) of items evaluated were rated as either Essential or Important. "Theme 2: cell membrane structure" was rated as less important than the other three themes. "Theme 4: membrane potential" was rated most difficult, while "theme 1: defining cell membranes" was rated as the easiest. The importance of cell membranes as a key aspect of biomedical education received strong support from Australian educators. The unpacking of the themes and subthemes within the cell membrane core concept provides guidance in the development of curricula and should facilitate better identification of the more challenging aspects within this core concept and help inform the time and resources required to support student learning. [This article was written with Task Force.]

Canonical transient receptor potential (TRPC) non-selective cation channels, particularly those assembled with TRPC3, TRPC6, and TRPC7 subunits, are coupled to Gαq-type G protein-coupled receptors for the major classes of excitatory neurotransmitters. Sustained activation of this TRPC channel-based pathophysiological signaling hub in neurons and glia likely contributes to prodigious excitotoxicity-driven secondary brain injury expansion. This was investigated in mouse models with selective Trpc gene knockout (KO). In adult cerebellar brain slices, application of glutamate and the class I metabotropic glutamate receptor agonist (S)-3,5-dihydroxyphenylglycine to Purkinje neurons expressing the GCaMP5g Ca2+ reporter demonstrated that the majority of the Ca2+ loading in the molecular layer dendritic arbors was attributable to the TRPC3 effector channels (Trpc3KO compared with wildtype (WT)). This Ca2+ dysregulation was associated with glutamate excitotoxicity causing progressive disruption of the Purkinje cell dendrites (significantly abated in a GAD67-GFP-Trpc3KO reporter brain slice model). Contribution of the Gαq-coupled TRPC channels to secondary brain injury was evaluated in a dual photothrombotic focal ischemic injury model targeting cerebellar and cerebral cortex regions, comparing day 4 post-injury in WT mice, Trpc3KO, and Trpc1/3/6/7 quadruple knockout (TrpcQKO), with immediate 2-h (primary) brain injury. Neuroprotection to secondary brain injury was afforded in both brain regions by Trpc3KO and TrpcQKO models, with the TrpcQKO showing greatest neuroprotection. These findings demonstrate the contribution of the Gαq-coupled TRPC effector mechanism to excitotoxicity-based secondary brain injury expansion, which is a primary driver for mortality and morbidity in stroke, traumatic brain injury, and epilepsy. [ABSTRACT FROM AUTHOR]

Long-term treatments to ameliorate peripheral neuropathic pain that includes mechanical allodynia are limited. While glial activation and altered nociceptive transmission within the spinal cord are associated with the pathogenesis of mechanical allodynia, changes in cortical circuits also accompany peripheral nerve injury and may represent additional therapeutic targets. Dendritic spine plasticity in the S1 cortex appears within days following nerve injury; however, the underlying cellular mechanisms of this plasticity and whether it has a causal relationship to allodynia remain unsolved. Furthermore, it is not known whether glial activation occurs within the S1 cortex following injury or whether it contributes to this S1 synaptic plasticity. Using in vivo 2-photon imaging with genetic and pharmacological manipulations of murine models, we have shown that sciatic nerve ligation induces a re-emergence of immature metabotropic glutamate receptor 5 (mGluR5) signaling in S1 astroglia, which elicits spontaneous somatic [Ca.sup.2+] transients, synaptogenic thrombospondin 1 (TSP-1) release, and synapse formation. This S1 astrocyte reactivation was evident only during the first week after injury and correlated with the temporal changes in S1 extracellular glutamate levels and dendritic spine turnover. Blocking the astrocytic mGluR5-signaling pathway suppressed mechanical allodynia, while activating this pathway in the absence of any peripheral injury induced long-lasting (>1 month) allodynia. We conclude that reawakened astrocytes are a key trigger for S1 circuit rewiring and that this contributes to neuropathic mechanical allodynia., Introduction Chronic pain and long-term memory share very similar mechanisms that involve neural circuit remodeling and synaptic plasticity as a key model (1, 2). The formation of new synaptic connections [...]

Aim: Inhaled nitrous oxide is a common form of procedural sedation in paediatric care. During the COVID‐19 pandemic, concerns about potential aerosol generation and associated viral transmission to health‐care workers have led to controversy regarding its use. We aimed to measure the degree of aerosol generation during continuous flow nitrous oxide sedation to inform future guidelines. Methods: Aerosol numbers in the respirable range were measured using a particle counter during 30 procedures undertaken in children under nitrous oxide sedation in the Emergency Department. Results: Changes from baseline measurements were greatest in particles in the 0.3 μm range. The mean increase from baseline in 0.3 μm particles per cubic metre was 18 022 (95% confidence interval (CI) 5949–30 096) after the child entered the room, and 2931 (95% CI −4407 to 10 269) during nitrous oxide administration. Conclusion: Variation of respirable particle numbers from baseline levels was no greater during nitrous oxide administration than for breathing and talking asymptomatic children. These results suggest the additional risk of airborne viral transmission to staff during inhaled nitrous oxide sedation is low. [ABSTRACT FROM AUTHOR]

Cyclic nucleotide-gated (CNG) channels play a critical role in olfactory and visual transduction. Site-directed mutagenesis and inside-out patch-clamp recordings were used to investigate ion pelmeation and selectivity in two mutant homomeric rat olfactory CNGA2 channels expressed in HEK 293 cells. A single point mutation of the negatively charged pore loop (P-loop) glutamate (E342) to either a positively charged lysine or arginine resuhed in functional channels, which consistently responded to cGMP, although the currents were generally extremely small. The concentration-response curve of the lysine mutant channel was very similar to that of wild-type (WT) channels, suggesting no major structural alteration to the mutant channels. Reversal potential measurements, during cytoplasmic NaCl dilutions, showed that the lysine and the arginine mutations switched the selectivity of the channel from cations ([P.sub.Cl]/[P.sub.Na] = 0.07 [WT]) to anions ([P.sub.Cl]/[P.sub.[Na] = 14 [Lys] or 10 [Arg]). Relative anion permeability sequences for the two mutant channels, measured with bi-ionic substitutions, were N[O.sub.3] > [I.sup.-] > [Br.sup.-] > [Cl.sup.-] > [F.sup.-] > [acetate.sup.-], the same as those obtained for anion-selective GABA and glycine channels. The mutant channels also seem to have an extremely small single-channel conductance, measured using noise analysis of about 1-2 pS, compared to a WT value of about 29 pS. The results showed that it is predominantly the charge of the E342 residue in the P-loop, rather than the pore helix dipoles, which controls the cation-anion selectivity of this channel. However, the outward rectification displayed by both mutant channels in symmetrical NaC1 solutions suggests that the negative ends of the pore helix dipoles may play a role in reducing the outward movement of [Cl.sup.-] ions through these anion-selective channels. These results have potential implications for the determinants of anion-cation selectivity in the large family of P-loop-containing channels.

Single mammalian neurons can be isolated with adherent functional synaptic terminals using an enzyme-free, mechanical dissociation procedure. This allows investigations of the effects of presynaptic modulators of synaptic transmission with unprecedented ease and accuracy. Furthermore, single presynaptic terminals and boutons can be visualized using fluorescent markers and can also be focally stimulated with electrical pulses. In this article, the isolated-nerve--adherent-synaptic-bouton preparation and some examples of its general properties and uses are discussed.

Members of the ligand-gated ion channel superfamily mediate fast synaptic transmission in the nervous system. In this study, we investigate the molecular determinants and mechanisms of ion permeation and ion charge selectivity in this family of channels by characterizing the single channel conductance and rectification of [alpha]1 homomeric human glycine receptor channels (GlyRs) containing pore mutations that impart cation selectivity. The A-1'E mutant GlyR and the selectivity double mutant ([SDM], A-1'E, P-2'[DELTA]) GlyR, had mean inward chord conductances (at -60 mV) of 7 pS and mean outward conductances of 11 and 12 pS (60 mV), respectively. This indicates that the mutations have not simply reduced anion permeability, but have replaced the previous anion conductance with a cation one. An additional mutation to neutralize the ring of positive charge at the extracellular mouth of the channel (SDM+R19'A GlyR) made the conductance-voltage relationship linear (14 pS at both 60 and -60 mV). When this external charged ring was made negative (SDM+R19'E GlyR), the inward conductance was further increased (to 22 pS) and now became sensitive to external divalent cations (being 32 pS in their absence). The effects of the mutations to the external ring of charge on conductance and rectification could be fit to a model where only the main external energy barrier height for permeation was changed. Mean outward conductances in the SDM+R19'A and SDM+R19'E GlyRs were increased when internal divalent cations were absent, consistent with the intracellular end of the pore being flanked by fixed negative charges. This supports our hypothesis that the ion charge selectivity mutations have inverted the electrostatic profile of the pore by introducing a negatively charged ring at the putative selectivity filter. These results also further confirm the role of external pore vestibule electrostatics in determining the conductance and rectification properties of the ligand-gated ion channels. KEY WORDS: ligand-gated ion channels * rings of charge * ion permeation * ion selectivity * M2 domain

Ligand-gated ion channel receptors mediate neuronal inhibition or excitation depending on their ion charge selectivity. An investigation into the determinants of ion charge selectivity of the anion-selective [alpha]1 homomeric glycine receptor ([alpha]1 glycine receptor [GlyR]) was undertaken using point mutations to residues lining the extra- and intracellular ends of the ion channel. Five mutant GlyRs were studied. A single substitution at the intracellular mouth of the channel (A-1'E GlyR) was sufficient to convert the channels to select cations over anions with [P.sub.Cl]/[P.sub.Na] = 0.34. This result delimits the selectivity filter and provides evidence that electrostatic interactions between permeating ions and pore residues are a critical factor in ion charge selectivity. The P-2'[DELTA] mutant GlyR retained its anion selectivity ([P.sub.Cl]/[P.sub.Na] = 3.81), but it was much reduced compared with the wild-type (WT) GlyR ([P.sub.Cl]/[P.sub.Na] = 27.9). When the A-1'E and the P-2'[DELTA] mutations were combined (selectivity double mutant [SDM] GlyR), the relative cation permeability was enhanced ([P.sub.Cl]/[P.sub.Na] = 0.13). The SDM GlyR was also [Ca.sup.2+] permeable ([P.sub.Ca]/[P.sub.Na] = 0.29). Neutralizing the extracellular mouth of the SDM GlyR ion channel (SDM+R19'A GlyR) produced a more [Ca.sup.2+]-permeable channel ([P.sub.Ca]/[P.sub.Na] = 0.73), without drastically altering monovalent charge selectivity ([P.sub.Cl]/[P.sub.Na] = 0.23). The SDM+R19'E GlyR, which introduces a negatively charged ring at the extracellular mouth of the channel, further enhanced [Ca.sup.2+] permeability ([P.sub.Ca]/[P.sub.Na] = 0.92), with little effect on monovalent selectivity ([P.sub.Cl]/[P.sub.Na] = 0.19). Estimates of the minimum pore diameter of the A-1'E, SDM, SDM+R19'A, and SDM+R19'E GlyRs revealed that these pores are larger than the [alpha]1 GlyR, with the SDM-based GlyRs being comparable in diameter to the cation-selective nicotinic acetylcholine receptors. This result provides evidence that the diameter of the ion channel is also an important factor in ion charge selectivity. KEY WORDS: ligand-gated ion channels * electrostatics * pore diameter * permeability * selectivity filter

Reduced anticonvulsant efficacy of benzodiazepines is a problem in the treatment of status epilepticus, with up to 50% of patients failing to respond to their first dose. KCC2 is a neuronal K+‐Cl− co‐transporter that helps set and maintain intracellular Cl− concentrations. KCC2 functional downregulation is a potential contributor to benzodiazepine resistance. We tested this idea using male and female doxycycline‐inducible, conditional transgenic mice to increase the functional expression of KCC2 in pyramidal neurons. We administered mice with two doses of the chemoconvulsant kainic acid (5 mg/kg, i.p.) 60 min apart and quantified the resultant seizures with electroencephalography (EEG) recordings. Overexpression of KCC2 prior to the chemoconvulsant challenge did not affect seizure latency or other measures of seizure severity, but it did increase diazepam's efficacy in stopping EEG seizures. Spike rate, time in seizure, and EEG spectral power following diazepam (5 mg/kg, i.p) were all significantly lower in KCC2 overexpression mice as compared to control mice. Our results indicate that, in the context of benzodiazepine resistance during sustained seizures, addressing impaired Cl− homeostasis alone appreciably improves the efficacy of γ‐aminobutyric acid (GABA)ergic inhibition. We therefore suggest the simultaneous targeting of KCC2 and GABAA receptors as a pathway for improving current anticonvulsant therapeutic strategies. [ABSTRACT FROM AUTHOR]

Coupling between the sulphonylurea receptor (SUR) and various potassium channels induces sulphonylurea sensitivity in inwardly-rectifying K-channels. Intrinsic channel activity is absent in the SUR of Xenopus oocyte and unable to induce ATP-sensitivity in endogenous potassium channels of HEK293 cells. The expression of SUR in HEK293 enhances the binding of (3H)glibenclamide. SUR regulates beta cell K-ATP channel activity and induces ATP-sensitivity in beta-cell K-ATP channels through nucleotide-binding.