Hypoxia and auto resuscitation in the neonatal rodent with special reference to the sympatho-adrenal system
Author: Yuan, Shi-Zeng
Date: 1999-01-25
Location: Astrid Lindgrens Barnsjukhus, Karolinska Sjukhuset
Time: 9.00
Department: Institutionen för kvinnors och barns hälsa / Department of Women's and Children's Health
Abstract
Preterm infants exhibit irregular breathing with frequent episodes of
apnea, which may be associated with cyanosis and bradycardia. Perinatal
asphyxia causes a considerable amount of morbidity and mortality that
occurs during early life. Studies of mechanisms responsible for perinatal
asphyxia are therefore very important. The main purpose of tile present
study has been to investigate physiological mechanisms during perinatal
asphyxia with special emphasis on respiration.
Anaesthetized newborn guinea pigs responded to hypoxia with a biphasic
response in ventilation, i.e., an initial increase followed by a
decrease. Cerebral activity was depressed during hypoxia. Regression
analysis showed a liner correlation between ventilation and cerebral
activity during hypoxia. Apnea occurred in some cases prior to the
depression of CFM activity, indicating that central control of
respiration off switch mechanism is activated during severe asphyxia.
During acute anoxia (100% N2), animals responded with hyperpnea, primary
apnea, hypoxic gasping and secondary apnea. One-day-old rats tolerated
anoxia much longer than 8- day-old. Adrenalectomy reduced the ability to
tolerate anoxia and autoresuscitation. This effect was also seen after
pretreatment with the [alpha]-receptor antagonist phentolamine, while the
ß-receptor antagonist propranolol did not show such effect. It seems that
intact adrenal function is important in maintaining proper duration of
gasping during anoxia and for autoreSUSCitation from anoxia during early
postnatal life. This underlying mechanism appears to involve
[alpha]-adrenergic receptors.
Supplementation with glucose prolonged the anoxic tolerance. However,
hyperglycaemia resulted in a reduced autoresuscitation. The difference in
survival rate seemed not to be attributed to accumulation of lactate in
the blood.
Labetalol and prazosin prolonged the gasping period during anoxia, but
lowered survival rate in the 8-day-old rats. Labetalol significantly
decreased BP and HR, while prazosin showed a tendency towards
hypotension. Autoresuscitation failed in the presence of anesthesia
indicating that general cerebral depression might abolish this mechanism.
These effects may involve [alpha]1-adrenergic receptor blockade. Since
labetalol is used in the clinic for the management of pregnancy- induced
hypertension these results may imply a potential risk of a failure of
autoresuscitation in the presence of perinatal asphyxia probably due to
the blockade of the life saving mechanisms evoked by catecholamines.
Severe asphyxia is often associated with hypoxic ischemic encephalopathy.
Brain damage developed after hypoxia-ischemia. Post-hypoxic treatment
with clonidine protected the neonatal brain from damage by 45%, while
labetalol, prazosin and idazoxan had no such effect.
Issue date: 1999-01-04
Publication year: 1999
ISBN: 91-628-3359-6
Statistics
Total Visits
Views | |
---|---|
Hypoxia ...(legacy) | 322 |
Hypoxia ... | 115 |
Total Visits Per Month
July 2020 | August 2020 | September 2020 | October 2020 | November 2020 | December 2020 | January 2021 | |
---|---|---|---|---|---|---|---|
Hypoxia ... | 2 | 1 | 1 | 2 | 0 | 5 | 1 |
Top country views
Views | |
---|---|
Sweden | 75 |
China | 59 |
Germany | 38 |
United States | 36 |
South Korea | 6 |
United Kingdom | 5 |
Hong Kong | 4 |
Brazil | 3 |
Canada | 3 |
Spain | 3 |
Top cities views
Views | |
---|---|
Kiez | 17 |
Shenzhen | 11 |
Beijing | 9 |
Sunnyvale | 7 |
Seoul | 6 |
Woodbridge | 6 |
Houston | 5 |
Tianjin | 4 |
Altea | 3 |
Easton | 3 |