Remodeling of skeletal muscle microvasculature in sickle cell trait and alpha-thalassemia.
The influence of sickle cell trait and/or alpha-thalassemia on skeletal muscle microvascular network characteristics was assessed and compared with control subjects [hemoglobin (Hb) AA] in 30 Cameroonian residents [10 HbAA, 5 HbAA alpha-thalassemia (alpha-t), 6 HbAS, and 9 HbASalpha-t] matched for maximal work capacity and daily energy expenditure. Subjects performed an incremental exercise to exhaustion and underwent a muscle biopsy. Muscle fiber type and surface area were not different among groups. However, sickle cell trait (SCT) was associated with lower capillary density (P < 0.05), lower capillary tortuosity (P < 0.001), and enlarged microvessels (P < 0.01). SCT carriers had reduced counts of microvessels <5-microm diameter, but a higher percentage of broader microvessels, i.e., diameter >10 microm (P < 0.05). alpha-Thalassemia seemed to be characterized by a higher capillary tortuosity and unchanged capillary density and diameter. Thus, while SCT is a priori clinically benign, we demonstrate for the first time that significant remodeling of the microvasculature occurs in SCT carriers. These modifications may possibly reflect protective adaptations against hemorheological and microcirculatory dysfunction induced by the presence of HbS. The remodeling of the microvascular network occurs to a lesser extent in alpha-thalassemia. In alpha-thalassemic subjects, increased capillary tortuosity would promote oxygen supply to muscle tissues and might compensate for the lower Hb content often reported in those subjects.
Vincent
Lucile
L
Laboratoire de Physiologie de l'Exercice, Université de Savoie, Chambéry, France.
Féasson
Léonard
L
Oyono-Enguéllé
Samuel
S
Banimbek
Viviane
V
Denis
Christian
C
Guarneri
Catherine
C
Aufradet
Emeline
E
Monchanin
Géraldine
G
Martin
Cyril
C
Gozal
David
D
Dohbobga
Macias
M
Wouassi
Dieudonné
D
Garet
Martin
M
Thiriet
Patrice
P
Messonnier
Laurent
L
D000328:Adult; D002196:Capillaries / Q000473:pathology* / Q000503:physiopathology; D016022:Case-Control Studies; D004734:Energy Metabolism / Q000502:physiology; D017079:Exercise Tolerance / Q000502:physiology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply*; D012039:Regional Blood Flow / Q000502:physiology; D012805:Sickle Cell Trait / Q000473:pathology* / Q000503:physiopathology; D014655:Vascular Resistance / Q000502:physiology; D014938:Work Capacity Evaluation; D017085:alpha-Thalassemia / Q000473:pathology* / Q000503:physiopathology