Insulin secretion and IP levels in two distant lineages of the genus Mus: comparisons with rat islets.
Islet responses of two different Mus geni, the laboratory mouse (Mus musculus) and a phylogenetically more ancient species (Mus caroli), were measured and compared with the responses of islets from rats (Rattus norvegicus). A minimal and flat second-phase response to 20 mM glucose was evoked from M. musculus islets, whereas a large rising second-phase response characterized rat islets. M. caroli responses were intermediate between these two extremes; a modest rising second-phase response to 20 mM glucose was observed. Prior, brief stimulation of rat islets with 20 mM glucose results in an amplified insulin secretory response to a subsequent 20 mM glucose challenge. No such potentiation or priming was observed from M. musculus islets. In contrast, M. caroli islets displayed a modest twofold potentiated first-phase response upon subsequent restimulation with 20 mM glucose. Inositol phosphate (IP) accumulation in response to 20 mM glucose stimulation in [(3)H]inositol-prelabeled rat or mouse islets paralleled the insulin secretory responses. The divergence in 20 mM glucose-induced insulin release between these species may be attributable to differences in phospholipase C-mediated IP accumulation in islets.
Zawalich
W S
WS
Yale University School of Nursing, New Haven, Connecticut 06536, USA. Walter.Zawalich@Yale.Edu
Zawalich
K C
KC
Tesz
G J
GJ
Sterpka
J A
JA
Philbrick
W M
WM
D000818:Animals; D005947:Glucose / Q000494:pharmacology; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D051379:Mice / Q000235:genetics* / Q000378:metabolism*; D008815:Mice, Inbred Strains; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013997:Time Factors; D010738:Type C Phospholipases / Q000378:metabolism
D007295:Inositol Phosphates; D007328:Insulin; D007527:Isoenzymes; D011493:Protein Kinase C; D010738:Type C Phospholipases; D005947:Glucose