Islet adaptations in fetal sheep persist following chronic exposure to high norepinephrine

  1. Sean W Limesand2
  1. 1Chongqing Key Laboratory of Forage & Herbivore, College of Animal Science and Technology, Southwest University, Chongqing, China
  2. 2School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
  3. 3Department of Physiology, University of Arizona, Tucson, Arizona, USA
  1. Correspondence should be addressed to S W Limesand; Email: limesand{at}
  1. Figure 1

    NE infusion inhibits insulin concentrations. Daily arterial means are presented for control (circles, n = 7) and NE fetuses (squares, n = 8). Values for plasma norepinephrine (A), plasma glucose (B), plasma insulin (C) and partial pressure of blood oxygen (PaO2, D) were determined for each day of treatment (x-axis). Difference (P < 0.05) during the infusion and post-infusion periods is identified with an asterisk.

  2. Figure 2

    Persistent enhancement of GSIS in NE fetuses. Plasma glucose and insulin concentrations are presented for the three GSIS studies, which are labeled above the graphs: before (GSIS-pre), 1 day after (GSIS-1d) and 5 days after (GSIS-5d) the chronic infusion. Baseline and hyperglycemic steady state period means for control (n = 6–7) and NE fetuses (n = 8) were analyzed within each GSIS study. Differences (P < 0.05) between control and NE fetuses within the period are identified (*).

  3. Figure 3

    Persistent enhancement of GPAIS in NE fetuses. Insulin concentrations are presented for the GPAIS studies in control (A, n = 6–7) and NE fetuses (B, n = 8). The arginine bolus is administered at time 0. GPAIS studies were conducted before (GPAIS-pre), 1 day after (GPAIS-1d) and 5 days after (GPAIS-5d) the chronic treatment. There was no study by time interaction. Study differences (*P < 0.05) for the average insulin concentration were observed in the NE fetuses but not controls.

  4. Figure 4

    Enhanced glucose-stimulated insulin secretion in NE islets. Pancreatic islets were isolated from control and NE fetuses (n = 6 animals/treatment). (A) Insulin secretion rates were measured in static incubations that contain 11.1 mmol/L glucose and various NE concentrations that ranged from 0 to 10 µmol/L (y-axis). The bar with asterisks indicate that the maximum insulin secretion rate was significantly different (P < 0.01) between control and NE islets. (B) The half maximal inhibitory concentration (IC50) was calculated for each treatment. Values represent means ± s.e.m., and the asterisks indicate a difference (P < 0.05) between treatment groups. (C) Islet insulin contents were not different between treatments.

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  1. J Endocrinol 232 285-295
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