Influence of age on surfactant isolated from healthy horses maintained on pasture.
BACKGROUND
Surfactant alterations are described in horses after exercise, anesthesia, and prolonged transport, in horses with recurrent airway obstruction, and in neonatal foals. The effect of horse age or bronchoalveolar lavage fluid (BALF) sample characteristics on surfactant is unknown.


OBJECTIVE
To evaluate surfactant phospholipid composition and function in healthy horses, and to investigate the influence of age and BALF sample characteristics on surfactant.


METHODS
Seventeen healthy horses 6-25 years of age maintained on pasture year-round.


METHODS
BALF was collected by standard procedures and was assessed for recovery volume, nucleated cell count (NCC), and cytology. Cell-free BALF was separated into crude surfactant pellet (CSP) and surfactant supernatant (Supe) by ultracentrifugation. Phospholipid and protein content were determined from both fractions. CSP phospholipid composition was analyzed by high-performance liquid chromatography with an evaporative light scatter detector. Surface tension of CSP was evaluated with a pulsating bubble surfactometer. Regression analysis was used to evaluate associations between age, BALF sample characteristics, and surfactant variables.


RESULTS
Results and conclusions were derived from 15 horses. Increasing age was associated with decreased phospholipid content in CSP but not Supe. Age did not affect protein content of CSP or Supe, or surfactant phospholipid composition or function. Age-related surfactant changes were unaffected by BALF recovery percentage, NCC, and cytological profile.


CONCLUSIONS
Older horses have decreased surfactant phospholipid content, which might be because of age-related pulmonary changes. Surfactant composition is unaffected by BALF sample characteristics at a BALF recovery percentage of at least 50%.
Christmann
U
U
Department of Large Animal Clinical Sciences, Virginia-Maryland Regional College of Veterinary Medicine, Blacksburg, VA 24061-0442, USA. chrisun@vt.edu
Hite
R D
RD
Witonsky
S G
SG
Elvinger
F
F
Werre
S R
SR
Thatcher
C D
CD
Tan
R H H
RH
Buechner-Maxwell
V A
VA
D000375:Aging / Q000502:physiology*; D000822:Animal Husbandry; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D006736:Horses / Q000502:physiology*; D011663:Pulmonary Surfactants / Q000032:analysis / Q000378:metabolism*
D011663:Pulmonary Surfactants