TY - JOUR
T1 - Maturational differences between vascular and bladder smooth muscle during ovine development
AU - Arens, Yvonne H J M
AU - Rosenfeld, Charles R.
AU - Kamm, Kristine E.
PY - 2000
Y1 - 2000
N2 - Maturation rates of vascular and visceral smooth muscle (SM) during ovine development were compared by quantifying contractile protein, myosin heavy chain (MHC) isoform contents, and contractile properties of aortas and bladders from female fetal (n = 19) and postnatal (n = 21) sheep. Actin, myosin, and protein contents rose progressively throughout development in both tissues (P ≤ 0.003); however, expression patterns differed. During the last trimester, i.e., 101-130 days (term ~145 days), bladder actin and MHC contents were approximately twofold greater (P < 0.04) than those in the aorta. Although the fractional content of 204-kDa SM1 MHC in the bladder decreased from 74 ± 3% at midgestation to 48 ± 2% 3 mo postnatal, the aorta exhibited an increase from 30 ± 2% to 65 ± 2%. Bladder MHC (MHC-B) migrating at 200 kDa contained only SM2 throughout development. In contrast, 200-kDa MHC in the aorta was predominantly nonmuscle MHC-B at midgestation, which was gradually replaced by SM2 as development progressed. Along with its early expression of SM2, bladder muscle obtained maximal stress generating capacity (1.7 x 105 N/m2) by term gestation, whereas the aorta exhibited no contractions until after birth. We conclude that whereas aortic SM maturation is delayed until after birth, bladder SM matures biochemically and functionally during prenatal development, thus supporting early requirements for micturition.
AB - Maturation rates of vascular and visceral smooth muscle (SM) during ovine development were compared by quantifying contractile protein, myosin heavy chain (MHC) isoform contents, and contractile properties of aortas and bladders from female fetal (n = 19) and postnatal (n = 21) sheep. Actin, myosin, and protein contents rose progressively throughout development in both tissues (P ≤ 0.003); however, expression patterns differed. During the last trimester, i.e., 101-130 days (term ~145 days), bladder actin and MHC contents were approximately twofold greater (P < 0.04) than those in the aorta. Although the fractional content of 204-kDa SM1 MHC in the bladder decreased from 74 ± 3% at midgestation to 48 ± 2% 3 mo postnatal, the aorta exhibited an increase from 30 ± 2% to 65 ± 2%. Bladder MHC (MHC-B) migrating at 200 kDa contained only SM2 throughout development. In contrast, 200-kDa MHC in the aorta was predominantly nonmuscle MHC-B at midgestation, which was gradually replaced by SM2 as development progressed. Along with its early expression of SM2, bladder muscle obtained maximal stress generating capacity (1.7 x 105 N/m2) by term gestation, whereas the aorta exhibited no contractions until after birth. We conclude that whereas aortic SM maturation is delayed until after birth, bladder SM matures biochemically and functionally during prenatal development, thus supporting early requirements for micturition.
KW - Actin
KW - Aorta
KW - Myosin
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U2 - 10.1152/ajpregu.2000.278.5.r1305
DO - 10.1152/ajpregu.2000.278.5.r1305
M3 - Article
C2 - 10801301
AN - SCOPUS:0034119477
SN - 0363-6119
VL - 278
SP - R1305-R1313
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 5 47-5
ER -