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Chronotropic function in spontaneously diabetic BB rats.

S Ramanadham·G M McGrath·J H McNeill
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Abstract

In the present study, isolated atrial function in spontaneously diabetic BB Wistar rats maintained for 12 weeks on a low (BB-LI) and a high (BB-HI) dosage of insulin was examined. Basal atrial rates were unchanged in the diabetic animals, relative to nondiabetic littermates (ND-BB) or Wistar controls. The BB-HI animals were euglycemic and responded to isoproterenol in a similar manner to the ND-BB and Wistar control animals. In contrast, BB-LI animals remained hyperglycemic and exhibited lower responses to the maximum chronotropic effects of isoproterenol. Plasma thyroid hormone levels were unaltered in the BB-diabetic animals. These results therefore reveal an absence of bradycardia and hypothyroidism in spontaneously diabetic BB rats, in contrast to previous observations in streptozotocin diabetic rats. However, a decrease in chronotropic response to isoproterenol was still noted in the BB-LI animals. These findings suggest that decreased positive chronotropic effect of isoproterenol in diabetes may not be a direct consequence of altered thyroid status.

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AnimalsBlood GlucoseBody WeightDiabetes Mellitus, ExperimentalHeart RateIsoproterenolMaleMyocardiumRatsRats, Inbred BBRats, Inbred StrainsJournal ArticleResearch Support, Non-U.S. Gov't

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S Ramanadham, G M McGrath, J H McNeill. 1989. Chronotropic function in spontaneously diabetic BB rats.. https://doi.org/10.1139/y89-082

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