Study on the mechanisms of Suaeda rigida polysaccharides on the heart inhibition and skeletal muscle promotion in the frog

Sha, A.L.; Hao, H.Y.

doi:10.1590/1678-4162-12481

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Arquivo Brasileiro de Medicina Veterinária e Zootecnia

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Veterinary Medicine • Arq. Bras. Med. Vet. Zootec. 74 (2) • Mar-Apr 2022 • https://doi.org/10.1590/1678-4162-12481 copy

Study on the mechanisms of Suaeda rigida polysaccharides on the heart inhibition and skeletal muscle promotion in the frog

[Estudo sobre os mecanismos dos polissacarídeos de Suaeda rigida na inibição do coração e promoção da musculatura esquelética no sapo]

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The objectives of this study were to investigate the effects of different concentrations of Suaeda rigida polysaccharides (SRPs) on the physiological characteristics of the frog heart and gastrocnemius muscle, compare their similarities and differences, and analyze the mechanisms. CaCl₂ and acetylcholine (Ach) were selected respectively to be co-incubated with the high concentration SRPs to observe the effects on the heart contraction of frog. The effects of different concentrations of the SRPs on the activities of acetylcholinesterase (A-CHE), Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase in the isolated frog heart were detected by UV-Vis spectrophotometry. The gastrocnemius muscle was immersed in the high concentration of SRPs for 10 min, and the systolic indexes were recorded. The effects of SRPs on the Ach content and A-CHE activity at the sciatic nerve-gastrocnemius junction were determined by UV-Vis spectrophotometry and enzyme-linked immunosorbent assay (ELISA). The results showed that the SRPs had significant inhibitory effects on the contractile amplitude of isolated heart and the contractile amplitude induced by CaCl₂ and Ach, respectively (P<0.01). The activity of Ca²⁺-Mg²⁺-ATPase was significantly promoted, and the activity of A-CHE was significantly inhibited (P<0.01). The contraction amplitude, contraction rate, relaxation rate of gastrocnemius muscle and the Ach content at the junction of sciatic nerve-gastrocnemius muscle were significantly increased (P<0.01), and the activity of A-CHE at the junction was significantly inhibited (P<0.01) by the SRPs. All the results suggested that the SRPs could inhibit the contraction of heart and promote the contraction and relaxation of skeletal muscle. The mechanism was related to blocking the fast I_Na channel, inhibiting the I_Ca-L and activating the M receptors of myocardial membrane and then inhibiting external Ca²⁺ influx, increasing Ca²⁺-Mg²⁺-ATPase activity, decreasing a-che activity.

Keywords:
Suaeda rigida polysaccharides; heart; sciatic nerve-gastrocnemius muscle; contraction; Ca²⁺; Ach

Groups	Concentrations／mg．ml ^-1	Contractile amplitude（g）		Inhibition rate (%)
Groups	Concentrations／mg．ml ^-1	Before administration	After administration
Low	5.00	3.96±0.38	1.89±0.35^**	52.34%
Intermediate	10.00	4.07±0.47	2.61±0.75^**	36.00%
High	20.00	4.06±0.27	1.20±0.51^**	70.31%

Groups	Concentrations／mg．ml ^-1	Heart rate（times·min^-1）		Rate of change (%)
Groups	Concentrations／mg．ml ^-1	Before administration	After administration
Low	5.00	30.67±2.88	27.67±4.23	-9.78%
Intermediate	10.00	32.00±3.58	34.00±3.58	6.25%
High	20.00	34.33±5.68	36.33±7.28	5.28%

	Before administration	Induced drugs	High SRPs	positive control
Systolic amplitude（g）	4.05±0.31	7.58±0.82^**（CaCl₂）	5.46±0.47^##	5.21±0.43^##( VPLh)
Systolic amplitude（g）	4.04±0.29	2.85±0.23^**（Ach）	2.04±0.18^##	1.90±0.14^##( PCPn)

Groups	Concentrations／mg．ml ^-1	A-CHE (U/mg)	Na⁺-K⁺-ATPase (U/mg)	Ca²⁺-Mg²⁺-ATPase (U/mg)
Control group	-	0.29±0.03	0.39±0.07	1.46±0.15
Low SRPs	5.00	0.22±0.03^**	0.44±0.08	1.82±0.30^*
Intermediate SRPs	10.00	0.18±0.02^**	0.41±0.10	2.13±0.34^**
High SRPs	20.00	0.13±0.04^**	0.43±0.07	2.40±0.28^**

Parameter	Before infiltration	After infiltration of the SRPs	Promotion rate (%)
Threshold stimulus (mV)	0.17±0.04	0.19±0.06	11.76%
Maximum stimulus (mV)	0.28±0.03	0.37±0.04^**	32.14%

Parameter	Before infiltration	After infiltration of the SRPs	Promotion rate (%)
Contraction latency (ms)	31.09±5.73	34.28±7.16	10.26%
Contractile amplitude (g)	7.52±0.93	13.40±1.05^**	78.19%
Contractile rate (g/ms)	0.16±0.02	0.29±0.04^**	81.25%
Relaxation rate (g/ms)	0.11±0.02	0.26±0.03^**	136.36%
Ach（umol/g）	1.76±0.22	2.95±0.51^**	67.61%
A-CHE（U/L）	94.08±9.73	43.46±6.25^**	-53.81%

Universidade Federal de Minas Gerais, Escola de Veterinária Caixa Postal 567, 30123-970 Belo Horizonte MG - Brazil, Tel.: (55 31) 3409-2041, Tel.: (55 31) 3409-2042 - Belo Horizonte - MG - Brazil
E-mail: abmvz.artigo@gmail.com

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[1] *Corresponding author: saldky@126.com