Origin of the potassium and voltage dependence of the cardiac inwardly rectifying K-current (IK1).

Using various voltage clamp protocols, we have examined the activation and deactivation kinetics of IK1 recorded in dissociated myocytes obtained from canine purkinje fibers. Exponential current relaxations following step changes of the membrane potential were characterized at several different K levels (5, 12, 42, and 82 mM) and several voltages (K reversal potential +/- 40 mV). We have interpreted our data according to a K-activated, K-channel model of IK1 gating. Our data suggests that at least two binding sites for extracellular K must be occupied before the channel opens and occupancy of about three more higher affinity sites for K on the open channel will slow the closing of that channel. In our model, the voltage dependency of gating arises from a combination of three voltage dependent steps: (a) isomerization between open and closed states, (b) binding of K, and (c) occupancy of the channel by internal Mg. Lowering internal K to 40 mM causes major changes in the voltage and K dependence of IK1 gating. However, these changes could be accounted for in our model by relatively small (approximately 20 to 30 mV) shifts in the voltage dependence of several of the steps that govern gating. Our data further suggest that there is an interaction between both extracellular and intracellular K levels and the ability of intracellular Mg to block the IK1 channel

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Care Home Safety Incidents and Safeguarding Reports Relating to Hospital to Care Home Transitions: A Retrospective Content Analysis

Copyright \ua9 2024 Wolters Kluwer Health, Inc. All rights reserved.Objective: The purpose of this study was to further the understanding of reported patient safety events at the interface between hospital and care home including what active failings and latent conditions were present and how reporting helped learning. Methods: Two care home organizations, one in the North East and one in the South West of England, participated in the study. Reports relating to a transition and where a patient safety event had occurred were sought during the COVID-19 (SARS-CoV-2) virus prepandemic and intrapandemic periods. All reports were screened for eligibility and analyzed using content analysis. Results: Seventeen South West England care homes and 15 North East England care homes sent 114 safety incident reports and after screening 91 were eligible for review. A hospital discharge transition (n = 78, 86%) was most common. Pressure damage (n = 29, 32%), medication errors (n = 26, 29%) and premature discharge (n = 21, 23%) contributed to 84% of the total reporting. Many ‘active failings’ (n = 340) were identified with fewer latent conditions (failings) (n = 14, 15%) being reported. No examples of individual learning were identified. Organization and systems learning were identified in 12 reports (n = 12, 13%). Conclusions: The findings highlight potentially high levels of underreporting. The most common safety incidents reported were pressure damage, medication errors, and premature discharge. Many active failings causing numerous staff actions were identified emphasizing the cost to patients and services. Additionally, latent conditions (failings) were not emphasized; similarly, evidence of learning from safety incidents was not addressed