New Zealand Journal of Agricultural Research abstracts
Tissue responsiveness and sensitivity to insulin in sheep fed plantain
and orchardgrass and exposed to cold
H. Sano1
Y. Tamura2
A. Shiga1
1Faculty of Agriculture
Iwate University
Morioka 020-8550, Japan
email: sano@iwate-u.ac.jp
2Tohoku National Agricultural Experiment
Station
Morioka 020-0123, Japan
Abstract To assess the effect on insulin action of feeding
a forage herb to sheep exposed to a cold environment, eight sheep were fed
either plantain (PL), a forage herb, or orchardgrass (OR), a forage. A hyperinsulinaemic
euglycaemic clamp procedure was applied to determine tissue responsiveness
and sensitivity to insulin in both the thermoneutral (20°C) and cold
(0-4°C) environments. For the glucose clamp procedure, insulin was infused
over four sequential 2-h periods at rates of 0.64, 1.6, 4.0, and 10 mU kg-0.75
body weight min-1 and glucose was infused at variable rates to
maintain euglycaemia. The maximal glucose infusion rate (tissue responsiveness
to insulin) was greater (P = 0.04) for the PL diet than for the OR diet,
and was enhanced (P = 0.001) during cold exposure. The plasma insulin concentration
at half maximal glucose infusion rate (tissue sensitivity to insulin) was
influenced by neither diet nor environment. No significant diet by environment
interaction was observed for these variables. It is possible that in sheep
the forage herb PL enhances insulin action through enhanced tissue responsiveness.
Insulin action in response to cold exposure was comparable between the PL
and OR diets.
Keywords herb; cold exposure; glucose clamp procedure;
insulin; plantain; sheep
A02056; Received 23 August 2002; accepted 13 May 2003; online publication
date 9 September 2003
New Zealand Journal of Agricultural Research, 2003, Vol. 46: 169-173
0028-8233/03/4603-0169 $7.00/0 © The Royal Society of New Zealand
2003
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