Dn. Herndon et al., LIPOLYSIS IN BURNED PATIENTS IS STIMULATED BY THE BETA(2)-RECEPTOR FOR CATECHOLAMINES, Archives of surgery, 129(12), 1994, pp. 1301-1305
Objective: To determine if the cardiovascular effects of excessive cat
echolamines could be selectively blocked in severely burned patients w
ithout adversely affecting protein or fat kinetics. Design: Prospectiv
e cohort study. Setting: A large tertiary care referral center in Galv
eston, Tex. Patients: Sixteen patients with greater than 40% body surf
ace area burns. Interventions: Patients were randomly selected to rece
ive propranolol hydrochloride, a nonselective beta(1)- and beta(2)-blo
cker, or metoprolol tartrate, a selective beta(1)-blocker. Main Outcom
e Measures: Heart rate; rate-pressure product; rate of appearance of u
rea, glucose, and leucine; and leucine oxidation were measured before
and after selective or nonselective beta-adrenergic blockade. Results:
Propranolol and metoprolol caused a significant decrease in heart rat
e, from a mean (+/-SD) of 143+/-15 to 115+/-11 and from 147+/-17 to 12
0+/-9 beats per minute, respectively, during the 5-day study period. N
either the rate of appearance of urea nor the rate of urea production
were significantly altered by propranolol or metoprolol therapy. Only
propranolol produced a significant decrease (P<.05) in the rate of app
earance of glycerol, from a mean (+/-SD) of 5.54+/-0.62 to 3.07+/-0.7
mu mol/kg per minute. The rate of appearance of leucine, used as an in
dex of total body protein catabolism, was not significantly altered by
either beta-blocker. Conclusions: Selective beta(1)-adrenergic blocka
de did not reduce lipolysis; however, a beta(1)- and beta(2)-adrenergi
c blockade significantly reduced lipolysis. Thus, the increased lipoly
sis, characteristic of severely burned patients, is caused by stimulat
ion of the beta(2)-adrenergic receptors for catecholamines.