ｶｴﾙ心臓八木式灌流法の定量的実験への改良 ―心拍出量測定から心電図同時記録まで―

伝統的な生理学実習項目の一つであるｶｴﾙ心臓の八木式灌流実験法に改良を加え､心室拍動をより定量的に観察記録できるようにした｡すなわち､収縮･拡張ｻｲｸﾙ中の心室の容積変化を気圧変化に変換して捉える簡便な装置(連通標本槽)を考案し､圧変化を拍出量の指標として連続描記できるようにした｡連通標本槽は心室を浸す槽と圧変化を発生する気密な槽とを連結したものである｡この方法により､前負荷の増減に適応する心拍出量の増減､すなわちﾌﾗﾝｸ･ｽﾀｰﾘﾝｸﾞ機構を明確に示すことができる｡また､大動脈内静水圧を増加させる装置を考案した｡これを用いることにより､後負荷増加に対応する心室拍動動態のﾕﾆｰｸな変化を観察できる｡さらに､この実験系における心電図の安定した記録法を考案した｡これにより心臓の機械的活動と電気的活動とを同時に対応させることができる｡われわれの新しい実験方法は､学生実習において学生に心臓の生理学･薬理学的性質を学ばせるために大変有用であろう｡The Yagi\u27s perfusion system has widely been used to study the beats of excised frog heart. Here, we describe a new method to obtain a measure of cardiac output of the frog heart perfused with the Yagi\u27s system. In the new method, the changes in ventricular volume during systole and diastole are converted to the changes in air pressure by using the communicating vessel chamber in which the tissue chamber bathing the ventricle is connected via a communicating tube to the air-tight chamber for pressure detection. With this method, the Frank-Starling mechanism associated with the changes in preload is clearly demonstrable. With an additional apparatus to increase the hydrostatic pressure within the aorta, it is possible to show the unique changes in ventricular dynamics accompanying the increases in afterload. In addition, a method to stably record the ECG simultaneously with the above measurement is described. Our new methods may be useful for the student practice in which students should learn the physiological as well as pharmacological properties of heart

Competencies That Japanese Collegiate Sports Coaches Require for Dual-Career Support for Student Athletes

The purpose of this study was to clarify coaches’ competencies (COM) regarding dual-career (DC) support for student athletes in Japan. The questionnaire survey was conducted at 31 universities with an online survey URL that was distributed to 300 collegiate athletic coaches. In total, there were 152 respondents (female, 19; male, 133; mean age, 43.15 ± 12.07 years; coaching experience, 12.83 ± 9.72 years). The online survey adopted a Japanese-translated version of the Dual-Career Competency Questionnaire (DCCQ), which has been translated into nine languages and is widely used in European counties. The scale consists of six factors and 33 items, each rated on a five-point scale of importance (IM) and possession (PO). The Japanese version of the DCCQ was validated through a confirmatory factor analysis, and the internal consistency of the items was confirmed by calculating the Cronbach’s alpha coefficient. In addition, we examined differences between the IM and PO for DC support by t-tests and by calculating effect sizes. The validity and reliability of the Japanese version of the DCCQ were confirmed based on the goodness-of-fit index and Cronbach’s alpha coefficients, respectively. Our examination of the differences between IM and PO in DC support revealed that coaches perceived the importance of DC support but did not possess the necessary COM to offer DC support. That finding was similar to those of previous European studies. In particular, the Japanese coaches who participated in our online survey recognized the importance of COM in terms of “collaboration with various stakeholders and departments” for DC support but did not feel as though they held sufficient COM in that regard. In other words, the improvement of DC support requires the development of a coaching program that fosters COM to work with various stakeholders. This key insight provides a direction and specific focus for programs to improve coaches’ DC support for student athletes

Conformational alterations in unidirectional ion transport of a light-driven chloride pump revealed using X-ray free electron lasers

光でイオンを輸送する膜タンパク質の巧妙な仕組み --XFELが捉えた光駆動型イオンポンプロドプシンの構造変化--. 京都大学プレスリリース. 2022-02-28.Light-driven chloride-pumping rhodopsins actively transport anions, including various halide ions, across cell membranes. Recent studies using time-resolved serial femtosecond crystallography (TR-SFX) have uncovered the structural changes and ion transfer mechanisms in light-driven cation-pumping rhodopsins. However, the mechanism by which the conformational changes pump an anion to achieve unidirectional ion transport, from the extracellular side to the cytoplasmic side, in anion-pumping rhodopsins remains enigmatic. We have collected TR-SFX data of Nonlabens marinus rhodopsin-3 (NM-R3), derived from a marine flavobacterium, at 10-µs and 1-ms time points after photoexcitation. Our structural analysis reveals the conformational alterations during ion transfer and after ion release. Movements of the retinal chromophore initially displace a conserved tryptophan to the cytoplasmic side of NM-R3, accompanied by a slight shift of the halide ion bound to the retinal. After ion release, the inward movements of helix C and helix G and the lateral displacements of the retinal block access to the extracellular side of NM-R3. Anomalous signal data have also been obtained from NM-R3 crystals containing iodide ions. The anomalous density maps provide insight into the halide binding site for ion transfer in NM-R3