Renal tubular glucose reabsorption is mediated by facilitative glucose transporter (GLUT) proteins and energy-dependent sodium glucose luminal transporters. Glucose transport in the diabetic kidney is upregulated and has been implicated in the pathogenesis of progressive diabetic nephropathy. Hyperglycemia, hypertension, and activation of the renin-angiotensin system are believed important in the development of the disease. The present study examines the renal expression of the facilitative glucose transporters GLUT1 and GLUT12 in rat models of diabetic nephropathy. Sprague-Dawley and transgenic (mRen-2)27 rats received either streptozotocin-induced diabetes or vehicle. GLUT12 expression and localization were determined by immunohistochemistry, immunoblotting, in situ hybridization, and confocal immunofluorescence. GLUT1 immunolabeling was detected on the basolateral membrane throughout the nephron. GLUT12 was localized to the distal tubules and collecting ducts. A significant increase in GLUT12 immunolabeling was measured in Ren-2 controls and Ren-2 diabetic animals compared with Sprague-Dawley controls. GLUT12 expression was higher in Ren-2 diabetic compared with Sprague-Dawley diabetic rats. Long-term diabetes resulted in significant increases in GLUT1 levels in the renal proximal tubules and expression was higher in Ren-2 diabetic than Sprague-Dawley diabetic rats. GLUT12 protein was localized to the cytoplasm and to the apical membrane of human and rat distal tubules and collecting ducts. The apical localization of GLUT12 in the distal tubules and collecting ducts suggests that it could contribute to additional glucose reabsorption in the late nephron. Levels of both GLUT1 and GLUT12 are elevated in animal models of hypertension and diabetic nephropathy.

Key points AMP‐activated protein kinase (AMPK) is considered a major regulator of skeletal muscle metabolism during exercise. However, we previously showed that, although AMPK activity increases by 8–10‐fold during ∼120 min of exercise at ∼65% V̇O2normalpeak in untrained individuals, there is no increase in these individuals after only 10 days of exercise training (longitudinal study). In a cross‐sectional study, we show that there is also a lack of activation of skeletal muscle AMPK during 120 min of cycling exercise at 65% V̇O2normalpeak in endurance‐trained individuals. These findings indicate that AMPK is not an important regulator of exercise metabolism during 120 min of exercise at 65% V̇O2normalpeak in endurance trained men. It is important that more energy is directed towards examining other potential regulators of exercise metabolism. Abstract AMP‐activated protein kinase (AMPK) is considered a major regulator of skeletal muscle metabolism during exercise. Indeed, AMPK is activated during exercise and activation of AMPK by 5‐aminoimidazole‐4‐carboxyamide‐ribonucleoside (AICAR) increases skeletal muscle glucose uptake and fat oxidation. However, we have previously shown that, although AMPK activity increases by 8–10‐fold during ∼120 min of exercise at ∼65% V̇O2normalpeak in untrained individuals, there is no increase in these individuals after only 10 days of exercise training (longitudinal study). In a cross‐sectional study, we examined whether there is also a lack of activation of skeletal muscle AMPK during 120 min of cycling exercise at 65% V̇O2normalpeak in endurance‐trained individuals. Eleven untrained (UT; V̇O2normalpeak = 37.9 ± 5.6 ml.kg−1 min−1) and seven endurance trained (ET; V̇O2normalpeak = 61.8 ± 2.2 ml.kg−1 min−1) males completed 120 min of cycling exercise at 66 ± 4% V̇O2normalpeak (UT: 100 ± 21 W; ET: 190 ± 15 W). Muscle biopsies were obtained at rest and following 30 and 120 min of exercise. Muscle glycogen was significantly (P < 0.05) higher before exercise in ET and decreased similarly during exercise in the ET and UT individuals. Exercise significantly increased calculated skeletal muscle free AMP content and more so in the UT individuals. Exercise significantly (P < 0.05) increased skeletal muscle AMPK α2 activity (4‐fold), AMPK αThr172 phosphorylation (2‐fold) and ACCβ Ser222 phosphorylation (2‐fold) in the UT individuals but not in the ET individuals. These findings indicate that AMPK is not an important regulator of exercise metabolism during 120 min of exercise at 65% V̇O2normalpeak in endurance trained men.

There is evidence that increasing carbohydrate (CHO) availability during exercise by raising preexercise muscle glycogen levels attenuates the activation of AMPKalpha2 during exercise in humans. Similarly, increasing glucose levels decreases AMPKalpha2 activity in rat skeletal muscle in vitro. We examined the effect of CHO ingestion on skeletal muscle AMPK signaling during exercise in nine active male subjects who completed two 120-min bouts of cycling exercise at 65 +/- 1% V(O2 peak). In a randomized, counterbalanced order, subjects ingested either an 8% CHO solution or a placebo solution during exercise. Compared with the placebo trial, CHO ingestion significantly (P < 0.05) increased plasma glucose levels and tracer-determined glucose disappearance. Exercise-induced increases in muscle-calculated free AMP (17.7- vs. 11.8-fold), muscle lactate (3.3- vs. 1.8-fold), and plasma epinephrine were reduced by CHO ingestion. However, the exercise-induced increases in skeletal muscle AMPKalpha2 activity, AMPKalpha2 Thr(172) phosphorylation and acetyl-CoA Ser(222) phosphorylation, were essentially identical in the two trials. These findings indicate that AMPK activation in skeletal muscle during exercise in humans is not sensitive to changes in plasma glucose levels in the normal range. Furthermore, the rise in plasma epinephrine levels in response to exercise was greatly suppressed by CHO ingestion without altering AMPK signaling, raising the possibility that epinephrine does not directly control AMPK activity during muscle contraction under these conditions in vivo.

In view of the current situation with a worldwide pandemic, the use of online teaching has become critical. This is difficult in the context of human anatomy, a subject contingent primarily on the use of human cadaveric tissues for learning through face-to-face practical laboratory sessions. Although anatomy has been taught using online resources including 3D models and anatomy applications, feedback from students and academic staff does not support the replacement of face-to-face teaching. At Charles Sturt University, we were obligated to cancel all classes on-campus in 2020 due to the COVID-19 pandemic. We ran exclusive online anatomy practical classes replacing classes usually run on campus. We designed an alternative program that consisted of twenty pre-recorded videos that were prepared in the anatomy laboratory using cadaveric tissues, and then discussed in live (and interactive) tutorials. Furthermore, innovative approaches to learning were shown and encouraged by the lecturer. Student survey responses indicated a positive response to both the anatomical videos and the innovative learning approaches. The results obtained by students showed a statistically significant increase in high distinctions and marked decrease in the amount of fail grades, compared with the previous three years (not online). The use of these videos and the encouragement of innovative learning approaches was a novel experience that will add valuable experiences for improved practice in online anatomy teaching. We propose that online anatomy videos of cadavers combined with innovative approaches are an efficient and engaging approach to replace face-to-face anatomy teaching under the current contexts.