Detection of multiple patterns of oscillatory oxygen consumption in single mouse islets of Langerhans.
A novel oxygen microsensor was used to measure oxygen levels in single mouse islets as a function of glucose concentration. Oxygen consumption of individual islets was 5.99 +/- 1.17, 9.21 +/- 2.15, and 12.22 +/- 2.16 pmol/min at 3, 10, and 20 mM glucose, respectively (mean +/- SEM, n = 10). Consumption of oxygen was islet-size dependent as larger islets consumed more oxygen than smaller islets but smaller islets consumed more oxygen per unit volume than larger islets. Elevating glucose levels from 3 to 10 mM induced pronounced fast oscillations in oxygen level (period of 12.1 +/- 1.7 s, n = 6) superimposed on top of large slow oscillations (period of 3.3 +/- 0.6 min, n = 6). The fast oscillations could be completely abolished by treatment with the L-type Ca2+-channel blocker nifedipine (40 microM) with a lesser effect on slow oscillations. Slow oscillations were almost completely dependent upon extracellular Ca2+. The oxygen patterns closely mimic those that have previously been reported for intracellular Ca2+ levels and are suggestive of an important role for Ca2+ in amplifying metabolic oscillations.
Jung
S K
SK
Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, USA.
Aspinwall
C A
CA
Kennedy
R T
RT
D000818:Animals; D015374:Biosensing Techniques; D002118:Calcium / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D019069:Cell Respiration / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D007515:Islets of Langerhans / Q000378:metabolism*; D051379:Mice; D009543:Nifedipine / Q000494:pharmacology; D010100:Oxygen / Q000032:analysis; D010101:Oxygen Consumption
D002121:Calcium Channel Blockers; D009543:Nifedipine; D005947:Glucose; D010100:Oxygen; D002118:Calcium