| Objective:1. To observe the inhibition of Radix Saposhnikoviae (RS) on the small intestinal propulsion (SIP) and gastric emptying (GE) in normal mice.2. To determine the effect of RS at different concentration on the contraction of smooth muscle strips and the Ca2+ mobilization of cultured smooth muscle cells of rat clone and the possible mechanism.Methods:1. Sixty mice were divided into control and five experimental groups randomly. Normal saline (NS) was used as control treatment while 5 dosages (5, 10, 15, 20, 25 g/kg) of RS were adopted for the experiment . The method for determination of phenol red was used to observe the SIP and GE. Those mice were sacrificed 30 min after intragastric administ ration and the small intestinal propulsion ratio (SIPR) and gastric residual ratio (GRR) of each group were observed.2. The colonic longitudinal muscle strips of rat were prepared and smooth muscle cells from colon of rat were isolated and cultured. In the experiment in vitro, the strips were suspended in organ bath and the contraction of strips was recorded. In the cell-experiment, the fluorescent intensity of intracellular Ca2+ of smooth muscle cells loaded with Fluo-4/AM was measured with laser scanning confocal microscope related software.Results:1. All of different dosages of RS had inhibition effect on the SIP and GE at different degrees in normal mice. For the SIPR, the difference between low-dosage (5, 10, 15 g/kg) groups and the NS group was significant (P < 0.05), and t he 15 g/kg group was the most powerful. As for the GRR, the difference between the NS group and the experimental groups (5, 10, 25 g/ kg) was significant (P < 0.05), while that between the NS group and the experimental groups (15, 20 g/kg) had no statistical value.2. In the experiment in vitro, inhibition of RS (0.02, 0.2, 2, 20 g/L) on strips had a concentration-dependent manner and RS 0.2, 2 and 20 g/L group had a significant difference from NS group (P < 0.01) for both Peak and Area. The inhibition of RS against Ach-induced contraction had same tendency. RS 2 and 20 g/L group (P < 0.01) for Peak while RS 0.02, 0.2, 2, 20 g/L group (P < 0.05) for Area had significant difference from control group. Naloxone+RS and Propranolol+RS group had significant difference from NS group (P < 0.01) while Phentolamine+RS group had significant difference from NS+RS group (P < 0.01). In the cell-experiment, the post-treatment FI of RS 0.2, 2, 20 g/L group had significant difference from pre-treatment FI (P < 0.05) and the inhibitory percentage of RS 2, 20 g/L group had significant difference from NS group (P < 0.01) in Ca2+-included buffer. In Ca2+-free buffer, neither the difference between post-treatment FI and pre-treatment FI nor that of inhibitory percentage between RS 0.02, 0.2, 2, 20 g/L group and NS group was significant.Conclusion:1. The inhibition of RS on SIP in mice has been proved to be possible, and the inhibition increased while the dosage was raised during the range of 5-15 g/kg but decreased during 15-25 g/kg. RS also inhibited GE to some extent, and the contribution descended during 5-15 g/kg but increased during 15-25 g/kg.2. RS showed inhibitory effects on spontaneous contraction of colonic smooth muscle strips of Rat in vitro. Its possible inhibitory mechanism had close relations with theα-adrenoceptor and perhaps with the M-cholinergic receptor, but had little relation with theβ-adrenoceptor and the opioid receptor. RS could prevent the mobilization of Ca2+ from extracellular into intracellular in some degree, but had no effect on the release of Ca2+ from sarcoplasmic reticulum and endoplasmic reticulum. |
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