Abstract
This study was performed to test the hypothesis that smaller reflex increases in vasopressin, cortisol, adrenocorticotropic hormone (ACTH), and angiotensin II (ANG II) concentrations are produced by hemorrhage in pregnant compared with nonpregnant conscious dogs. Equivalent hemorrhages (1% of the initial blood volume per minute) produced larger decreases in arterial pressure [P < 0.01; 107 ± 6 to 73 ± 10 mmHg (pregnant); 109 ± 6 to 90 ± 5 mmHg (nonpregnant)] but produced similar increases in plasma vasopressin concentration in the pregnant animals. As a result, the slope of the arterial pressure-to-vasopressin relationship was reduced (P < 0.05). During pregnancy, smaller increases in plasma cortisol concentration and heart rate were also produced for a given decrease in arterial pressure, but the relationship between pressure and ACTH was not significantly affected. In contrast, higher levels of plasma renin activity and plasma ANG II concentration were achieved in the pregnant dogs. In general, the relationships between plasma hormone levels and either left or right atrial pressure were not significantly altered. These results indicate that reflex increases in heart rate, vasopressin, and cortisol concentration are attenuated in pregnant dogs and that this attenuation may contribute to the inability of pregnant animals to achieve normal cardiovascular homeostasis during hemorrhage.
Original language | English (US) |
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Pages (from-to) | H1610-H1619 |
Journal | American Journal of Physiology - Heart and Circulatory Physiology |
Volume | 266 |
Issue number | 4 35-4 |
DOIs | |
State | Published - 1994 |
Keywords
- adrenocorticotropic hormone
- angiotensin II
- blood pressure
- cortisol
- heart rate
- renin
- sympathetic nervous system
ASJC Scopus subject areas
- Physiology
- Cardiology and Cardiovascular Medicine
- Physiology (medical)