Fig. 5.

MLCK velocity in intact ovine carotid arteries. Fetal and adult artery segments were wire mounted and positioned in a custom-made rapid freeze apparatus, activated via electrical field stimulation, and frozen at exactly 0, 1, 2, and 3 s using a computer-controlled apparatus. The segments were then analyzed for MLC₂₀ phosphorylation. The initial rate of change of MLC₂₀ phosphorylation was taken as a measure of MLCK velocity (top). To correct for age-related differences in MLC₂₀ and MLCK abundances, the %MLC₂₀ phosphorylation ratios were multiplied by the corresponding mass ratios of MLC₂₀/MLCK abundance to obtain units of ng MLC₂₀ phosphorylated/ng MLCK (bottom). The initial slopes (V) are given for each age group. A total of 20 artery segments from 5 fetuses and 20 artery segments from 5 adults were used for this protocol. Values indicate averages ± SE. *P < 0.05, significant difference between corresponding fetal and adult value. Error bars for adult values at bottom are smaller than the size of the symbols.