Sarcolemmal glucose transport in Ca2+-tolerant myocytes from adult rat heart. Calcium dependence of insulin action

Isolated muscle cells from adult rat heart were used to study the relationship between myocardial insulin processing and insulin action on 3-O-methylglucose transport at 37 degrees C. Internalization of the hormone as measured by determination of the non-dissociable fraction of cell-bound insulin increased linearly up to 10 min, reaching a plateau by 30-60 min at 3 nM-insulin. At this hormone concentration the onset of insulin action was found to be biphasic, with a rapid phase up to 8 min, followed by a much slower phase, reaching maximal insulin action by 30-60 min. Insulin internalization was totally blocked by phenylarsine oxide, whereas dansylcadaverine had no effect on this process. Initial insulin action (5 min) on glucose transport was not affected by chloroquine and dansylcadaverine, but was completely abolished by treatment of cardiocytes with phenylarsine oxide. This drug effect was partly prevented by the presence of 2,3-dimercaptopropanol. Under steady-state conditions (60 min), the stimulatory action of insulin was decreased by about 60% by both chloroquine and dansylcadaverine. This study, demonstrates that insulin action on cardiac glucose transport is mediated by processing of the hormone. The data suggest dual pathways of insulin action involving initial processing of hormone-receptor complexes and lysosomal degradation.

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Regulation of glucose transport in Ca2+-tolerant myocytes from adult rat heart

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research ◽

10.1016/0167-4889(85)90067-9 ◽

1985 ◽

Vol 846 (2) ◽

pp. 208-215 ◽

Cited By ~ 10

Author(s):

I. Bihler ◽

S.R. McNevin ◽

P.C. Sawh

Keyword(s):

Glucose Transport ◽

Rat Heart ◽

Adult Rat

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Insulin action on the glucose transport system in isolated cardiocytes from adult rat

Biochemical Journal ◽

10.1042/bj2120385 ◽

1983 ◽

Vol 212 (2) ◽

pp. 385-392 ◽

Cited By ~ 59

Author(s):

J Eckel ◽

G Pandalis ◽

H Reinauer

Keyword(s):

Glucose Transport ◽

Transport System ◽

Insulin Action ◽

Maximal Response ◽

Lag Phase ◽

Maximal Velocity ◽

Intracellular Magnesium ◽

Adult Rat ◽

Maximal Stimulation ◽

Glucose Transport System

Calcium-tolerant myocytes from the adult rat heart were used to study the effects of insulin on the kinetics of myocardial 3-0-methylglucose transport at 37 degrees C. Insulin increased the initial velocity of sugar influx without affecting the equilibrium uptake values. Maximal stimulation averaged 50-80%, with a half-maximal response at an insulin concentration of 0.1 nM and maximal stimulation occurring at 1 nM. The onset of insulin action was preceded by a lag-phase of 20 s, reaching maximal action by 60 s. The Vmax. of the glucose transport system was increased from 160 to 287 nmol/min per 10(6) cells with an unaltered affinity. Neither extracellular nor intracellular calcium was found to be involved in the stimulatory action of insulin. Removal of intracellular magnesium resulted in a loss of insulin action. This study demonstrates that activation of the cardiac glucose transporter by insulin is due exclusively to an increase in the maximal velocity representing one of the very early effects of insulin on myocardial metabolism. The data suggest involvement of magnesium in the transmission of the insulin signal.

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Effect of Insulin on Proximal Tubules Handling of Glucose: A Systematic Review

Journal of Diabetes Research ◽

10.1155/2020/8492467 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17 ◽

Cited By ~ 1

Author(s):

Ricardo Pereira-Moreira ◽

Elza Muscelli

Keyword(s):

Glucose Transport ◽

Insulin Action ◽

Current Knowledge ◽

Sglt2 Inhibitor ◽

Proximal Tubules ◽

Human Studies ◽

Glucose Disposal ◽

Diabetic Patients ◽

Insulin Effect ◽

Renal Gluconeogenesis

Renal proximal tubules reabsorb glucose from the glomerular filtrate and release it back into the circulation. Modulation of glomerular filtration and renal glucose disposal are some of the insulin actions, but little is known about a possible insulin effect on tubular glucose reabsorption. This review is aimed at synthesizing the current knowledge about insulin action on glucose handling by proximal tubules. Method. A systematic article selection from Medline (PubMed) and Embase between 2008 and 2019. 180 selected articles were clustered into topics (renal insulin handling, proximal tubule glucose transport, renal gluconeogenesis, and renal insulin resistance). Summary of Results. Insulin upregulates its renal uptake and degradation, and there is probably a renal site-specific insulin action and resistance; studies in diabetic animal models suggest that insulin increases renal SGLT2 protein content; in vivo human studies on glucose transport are few, and results of glucose transporter protein and mRNA contents are conflicting in human kidney biopsies; maximum renal glucose reabsorptive capacity is higher in diabetic patients than in healthy subjects; glucose stimulates SGLT1, SGLT2, and GLUT2 in renal cell cultures while insulin raises SGLT2 protein availability and activity and seems to directly inhibit the SGLT1 activity despite it activating this transporter indirectly. Besides, insulin regulates SGLT2 inhibitor bioavailability, inhibits renal gluconeogenesis, and interferes with Na+K+ATPase activity impacting on glucose transport. Conclusion. Available data points to an important insulin participation in renal glucose handling, including tubular glucose transport, but human studies with reproducible and comparable method are still needed.

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