Table 8.

Related Calcium-Dependent Contractile Mechanisms with Development

Physiologic Variable	Fetus	Newborn	Adult	Reference
Gqα expression (in rat portal vein, % adult value)		400 to 500	100	[448]
Ins (1,4,5)P3-induced contraction (% Ca2+-induced maximum)	9±2 (35)		26±5	[357]
Ins(1,4,5)P3 Response to Norepinephrine (% of Basal)	345±27 (97)		355±23	[407]
Ins(1,4,5)P3 ·α1-AR−1	5.2±1.0c (45)		11.5±1.0	[407]
Ins(1,4,5)P3-Receptor Density (fmol·mg protein−1)	115±15 (116)		99±5	[449]
Ca2+ Mass (nmol·mg dry wt−1)	12±2b (400)		3±1	[354]
Ca2+ Mass of Ins(1,4,5)P3-Sensitive pool	1.6±0.2 (94)		1.7±0.2	[354]
Ca2+ Mass of Ryanodine-Sensitive Pool	1.2±0.1b (1200)		0.1±0.1	[354]
Calcium “sparks”	Significantly less	Significantly less	Control value	[378]
MLCK concentration (10−6M)*	1.8±0.1b (22)		8.2±0.6	[450]
(normalized to fetal value)	1.0 (26)		3.8±0.7	[451]
MLCK maximum velocity (ng MLC phosphorylated · ng MLCK−1)*	1.52±0.2b (585)		0.26±0.01	[450]
MLCK In situ Fractional Activation*	9.1±0.8b (535)		1.7±0.2	[450]
Total MLCK activity (% MLC20 phosphorylated · sec−1)*	7.39±0.53 (89)		6.56±0.29	[450]
MLCP Concentration (normalized to fetal value)	1.0 (56)		1.8±0.2	[451]
MLC20 concentration (10−6M)*	236±44 (119)		198±28	[450]
Phosphorylated/Total MLC20 (% Adult Value)	(64)		100	[9]
CPI-17 – Total (% Adult Value)	(15)		100	[9]
Calmodulin concentration (10−6M)*	12.4±1.3b (41)		30.6±3.7	[450]
(normalized to fetal value)	1.0 (31)		3.2±0.7	[451]
HSP-27 (normalized to fetal value)	1.0 (50)		2.0±0.2	[451]

Values are mean ±SE or 5 or more in each group;

Values in parentheses represent % of adult value;

Significantly different from adult value:

^bP<0.01;

^cP<0.05;

^*CCA