Role of intracellular calcium in contraction of internal anal sphincter

Table 1 Dose-response correlation of Ach and NA in colonic smooth muscle and IAS (^-x±s, n = 10)

Colonic smooth muscle		Internal anal sphincter (IAS)
Ach (mol/L)	Contraction strength (g)	NA (mol/L)	Contraction strength (g)
10-6	1.2 ± 0.39	10-6	0.70 ± 0.23
10-5	2.4 ± 0.41	5 × 10-6	1.34 ± 0.41
10-4	4.1 ± 1.20	10-5	1.74 ± 0.41
10-3	6.4 ± 1.60	5 × 10-5	2.20 ± 0.44
10-2	9.3 ± 1.75	10-4	2.68 ± 0.45

Table 2 Contraction of colonic smooth muscle and IAS in different solutions (^-x±s, n = 10)

Solution	Contraction strength (g)
	Colonic smooth muscle	Internal anal sphincter
Ca2+ solution	8.30 ± 2.01	2.44 ± 1.20
Ca2+ -free solution	4.27 ± 0.91a	1.84 ± 0.77

^aP < 0.01, t = 3.72, compared with Ca²⁺ containing solution.

Table 3 Inhibiting effect of ryandine on colonic smooth muscle and IAS (^-x±s, n = 10)

Ryanodine (μmol/L)	Percentage of contractile strength without ryanodine (%)
	Colonic smooth muscle	Internal anal sphincter (IAS)
0.1a	85 ± 17.9	91 ± 11
1.0	87 ± 13	71 ± 24b
10.0	85 ± 14	57 ± 20c

^bP < 0.05, t = 2.48;

^cP < 0.01, t = 3.61; compared with a.