The effect of sympatholytics on uncontrolled hemorrhage.
OBJECTIVE
To assess the possible benefits of sympatholytics on uncontrolled hemorrhage in unanesthetized rats.


METHODS
A randomized laboratory study using rats to test the effects of sympatholytics on uncontrolled hemorrhage.


METHODS
Research laboratory.


METHODS
Forty female Sprague-Dawley rats, randomly assigned into four groups according to the treatment: untreated (Control); alpha-adrenergic blockade with phenoxybenzamine (Alpha); beta-adrenergic blockade with propranolol (Beta); and a combined alpha- and beta-adrenergic blockade by phenoxybenzamine and propranolol (Alpha/Beta).


METHODS
After cannulation under light ether, the rats were allowed to awaken. A baseline blood sample was withdrawn. The uncontrolled hemorrhage was initiated by tail resection and allowed to continue without intervention for the duration of the experiment. After 15 mins, 80 mL/kg isotonic saline fluid was infused at 4.4 mL/min. At 60 mins, another blood sample was drawn; changes in mean arterial pressure, hematocrit, blood loss, and mortality were observed for up to 180 mins.


METHODS
Survival, mortality, blood loss (amount, prevalence, and rate), and hemodynamic variables (mean arterial pressure, pulse rate, hematocrit).


RESULTS
In the Alpha group, there was a reduction in spontaneous blood loss compared with the control group (2.9 vs. 10.6 mL/kg, respectively) and 100% survival. In contrast, the Beta group exhibited an increase in tail blood loss (21.1 mL) and a decreased survival (10%). Despite the enhanced hemorrhage in the Alpha/Beta group (17.0 mL/kg) compared with controls, the survival rate in both of these groups was 60%. In all groups, no significant increase in tail blood loss was observed after 60 mins.


CONCLUSIONS
An alpha-adrenergic blockade increased survival in uncontrolled hemorrhage by significantly reducing spontaneous blood loss. Conversely, a beta-adrenergic blockade significantly decreased survival and increased blood loss, whereas a combined blockade significantly increased blood loss without affecting survival.
Rudé
M J
MJ
Department of Surgery, the Texas Tech University Health Sciences Center, Lubbock 79430, USA.
Soucy
D M
DM
Hagedorn
F
F
Illner
H
H
Shires
G T
GT
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000009:adverse effects*; D000818:Animals; D004195:Disease Models, Animal; D004359:Drug Therapy, Combination; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006470:Hemorrhage / Q000188:drug therapy* / Q000401:mortality; D010643:Phenoxybenzamine / Q000494:pharmacology*; D011433:Propranolol / Q000009:adverse effects*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015996:Survival Rate; D013565:Sympatholytics / Q000494:pharmacology*; D013997:Time Factors
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D013565:Sympatholytics; D010643:Phenoxybenzamine; D011433:Propranolol