Effect of Potassium-Magnesium Sulfate on Intestinal Dissociation and Absorption Rate, Immune Function, and Expression of NLRP3 Inflammasome, Aquaporins and Ion Channels in Weaned Piglets

Abstract

This study investigated the effects of potassium magnesium sulfate (PMS) on intestinal dissociation and absorption rate, immune function, and expression of the NOD-like receptor thermal domain-associated protein 3 (NLRP3) inflammasome, aquaporins (AQPs), and potassium and magnesium ion channels in weaned piglets. Experiment 1 involved the assessment of the dissociation rate of PMS in pig digestive fluid and the absorption rate of PMS in the small intestine using an Ussing chamber in vitro. In Experiment 2, 216 healthy 21-day-old weaned piglets were selected and randomly assigned to six groups (0%, 0.15%, 0.30%, 0.45%, 0.60%, and 0.75% PMS), with each group 6 replicates of six piglets per replicate. The in vitro Ussing chamber results indicated that the absorption of K⁺ and Mg²⁺ in the jejunum and ileum was significantly higher than that in the duodenum (p < 0.05). The in vivo study demonstrated that the addition of PMS resulted in a linear increase in serum K⁺, IgG, and interleukin (IL)-2 levels while simultaneously reducing serum IL-1β levels (p < 0.05). Dietary PMS significantly elevated serum IL-10 and Mg²⁺ levels in feces (p < 0.05). Furthermore, supplementation with 0.60% or 0.75% PMS significantly downregulated the mRNA expression of NLRP3 in the jejunum (p < 0.05). Dietary PMS supplementation linearly reduced the mRNA expression levels of cysteine protease 1 (Caspase-1) and IL-1β in both the jejunum and colon as well as the mRNA expression levels of two-pore domain channel subfamily K member 5 (KCNK5) in these regions (p < 0.05). Notably, supplementation with 0.15% PMS significantly decreased the mRNA expression of transient receptor potential channel 6 (TRPM6) in the jejunum and significantly increased the expression of TRPM6 in the colon (p < 0.05). Dietary addition of 0.45% and 0.60% PMS significantly increased the mRNA expression of aquaporin 3 (AQP3) in the colon (p < 0.05), whereas 0.75% PMS significantly increased the mRNA expression of aquaporin 8 (AQP8) in both the jejunum and colon. Moreover, the expression levels of AQP3 and AQP8 were significantly negatively correlated with the diarrhea rate observed between days 29 and 42. In conclusion, dietary PMS supplementation improved immune function, inhibited the activation of intestinal NLRP3, and modulated the expression of water and ion channels in weaned piglets, thereby contributing to the maintenance of intestinal water and ion homeostasis, which could potentially alleviate post-weaning diarrhea in piglets. The recommended supplemental level of PMS in the corn-soybean basal diet for weaned piglets is 0.30%.

Keywords: NLPR3; aquaporins; ion channel; magnesium potassium sulfate; weaned piglets.

Figure 1

Dissociation concentrations of PMS, K₂SO₄, and MgSO₄ in simulated pig gastric juice. Solutions of PMS, K₂SO₄, and MgSO₄ were added separately to three individual samples of pig gastric juice (100 mL, 37 °C, K⁺ 0.05238 g/mL, Mg²⁺ 0.0162 g/mL). Then, the dissociation solutions of the three groups (n = 3) were collected to measure the concentrations of K⁺ and Mg²⁺ in the dissociation solutions at various time points (10 s, 20 s, 30 s, 1 min, 5 min, and 10 min). PMS, potassium magnesium sulfate.

Figure 2

Residual concentrations of potassium and magnesium ions in different intestinal mucosa and serous sides of weaned piglets. The duodenum, jejunum, and ileum segments (2 cm²) from 21-day-old weaned piglets were used to investigate the absorption of PMS, K₂SO₄, and MgSO₄ in Krebs solution using Ussing chamber assay (n = 3). PMS, potassium magnesium sulfate.

Figure 3

Potassium and magnesium absorption by PMS, K₂SO₄, and MgSO₄ in the intestine. PMS: potassium magnesium sulfate. * indicates significant difference between the two groups (p < 0.05) (n = 3).

Figure 4

Effect of dietary PMS supplementation on the contents of potassium and magnesium ions in the serum and feces of weaned piglets. CON, basal diet; 0.15%, diet containing 0.15% PMS; 0.3%, diet containing 0.3% PMS; 0.45%, diet containing 0.45% PMS; 0.6%, diet containing 0.6% PMS; 0.75%, diet containing 0.75% PMS. PMS: potassium magnesium sulfate. ^a,b Means in columns without a common superscript letter differ significantly at p < 0.05. Data are presented as mean ± SE (n = 6).

Figure 5

Effect of dietary PMS supplementation on intestinal expression of NLRP3 inflammasome in weaned piglets. (a) Jejunum. (b) Colon. PMS, Potassium–magnesium sulfate; NLRP3, NOD-like receptor thermal domain-associated protein 3; ASC, apoptosis-associated speck-like protein containing a CARD; Caspase-1, cysteine protease 1; IL-1β, interleukin-1β. CON, basal diet; 0.15%, diet containing 0.15% PMS; 0.3%, diet containing 0.3% PMS; 0.45%, diet containing 0.45% PMS; 0.6%, diet containing 0.6% PMS; 0.75%, diet containing 0.75% PMS. ^a,b Means in columns without a common superscript letter differ significantly at p < 0.05. Data are presented as mean ± SE (n = 6).

Figure 6

Effect of PMS on mRNA expression of potassium channels in the jejunum and colon of weaned piglets. (a) Jejunum. (b) Colon. PMS, potassium magnesium sulfate; KCNK5, potassium channel subfamily K member 5; KCNK6, potassium channel subfamily K member 6; KCNK12, potassium channel subfamily K member 12. CON, basal diet; 0.15%, diet containing 0.15% PMS; 0.3%, diet containing 0.3% PMS; 0.45%, diet containing 0.45% PMS; 0.6, diet containing 0.6% PMS; 0.75%, diet containing 0.75% PMS. Data are presented as mean ± SE (n = 6).

Figure 7

Effect of PMS on mRNA expression of magnesium channels in the jejunum and colon of weaned piglets. (a) Jejunum. (b) Colon. PMS, Potassium–magnesium sulfate; TRPM6, transient receptor potential cation channel, subfamily M, member 6; TRPM7, transient receptor potential cation channel, subfamily M, member 7; MagT1, magnesium transporter 1. CON, basal diet; 0.15%:, diet containing 0.15% PMS; 0.3%, diet containing 0.3% PMS; 0.45%, diet containing 0.45% PMS; 0.6%, diet containing 0.6% PMS; 0.75%, diet containing 0.75% PMS. ^a,b,c Means in columns without a common superscript letter differ at p < 0.05. Data are presented as mean ± SE (n = 6).

Figure 8

Effect of PMS on mRNA expression of aquaporins in the jejunum and colon of weaned piglets. (a) Jejunum. (b) Colon. PMS, Potassium–magnesium sulfate; AQP1, aquaporin 1; AQP3, aquaporin 3; AQP7, aquaporin 7; AQP8, aquaporin 8. CON, basal diet; 0.15%, diet containing 0.15% PMS; 0.3%, diet containing 0.3% PMS; 0.45%, diet containing 0.45% PMS; 0.6%, diet containing 0.6% PMS; 0.75%, diet containing 0.75% PMS. ^a,b Means in columns without a common superscript letter differ at p < 0.05. Data are presented as mean ± SE (n = 6).

Figure 9

Spearman’s correlation analysis between the incidence of diarrhea and intestinal aquaporin expression in weaned piglets. (a) Correlation between intestinal aquaporin-3 (AQP3) and diarrhea rate in piglets at 29–42 d. (b) Correlation between intestinal aquaporin-8 (AQP8) and diarrhea rate in piglets at 29–42 d. PMS, potassium magnesium sulfate.