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Developmentally regulated effects of severe hemorrhage on cardiovascular homeostasis and the arterial baroreflex control of heart rate

Physiological Reports, ISSN: 2051-817X, Vol: 3, Issue: 7, Page: e12440
2015
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    Citations
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  • 11
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    Social Media
Metric Options:   Counts1 Year3 Year

Metrics Details

  • Citations
    1
  • Captures
    11
  • Social Media
    1
    • Shares, Likes & Comments
      1
      • Facebook
        1

Article Description

The purpose of this study was to investigate in developing animals, the cardiovascular responses to severe hemorrhage at which compensatory mechanisms fail and when blood pressure remains decreased after blood loss. Two groups of conscious lambs (Group I: one to two weeks, N = 7; group II: six to seven weeks, N = 7) were studied. Mean arterial pressure, systolic and diastolic pressures, and heart rate were measured for 20 min before (Control, C) and for 60 min after a fixed hemorrhage of 30% of blood volume. The arterial baroreflex control of heart rate was assessed before (C), and at 30 and 60 min intervals after hemorrhage. Mean arterial pressure decreased for up to 60 min after hemorrhage in both groups of lambs. In group I, heart rate decreased from 200 ± 29 (C) to 164 ± 24 beat min at 30 min then increased to 232 ± 45 beat min at 60 min, whereas heart rate remained unaltered in group II. With respect to the arterial baroreflex control of heart rate, by 30 min after hemorrhage in group I, there was a decrease in the heart rate range over which the baroreflex operates (P1) from 192 ± 13 (C) to 102 ± 9 beats min; by 60 min after hemorrhage, there was a decrease in minimum heart rate (P4) from 72 ± 10 (C) to 32 ± 25 beats min. In group II, P1 decreased to a lesser extent than group I from 134 ± 21 (C) to 82 ± 10 beats min at 30 min; minimum heart rate (P4) decreased from 40 ± 15 (C) to 24 ± 9 and 20 ± 13 beats min at 30 and 60 min, respectively. These results provide the first assessment of the arterial baroreflex control of heart rate following blood loss and new evidence that the cardiovascular responses to severe hemorrhage are developmentally regulated.

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