Potassium and insulin affect the contractility of abomasal smooth muscle

Abstract

Abomasal displacement is a frequent and important disease of high yielding dairy cows. Although several factors are related to its occurrence, the pathogenesis of the condition is still inadequately understood, particularly in regard to K(+) and insulin homeostasis. For this reason the aim was to investigate the effects of K(+) and insulin concentrations on in vitro motility of abomasal smooth muscle. The second aim was to determine whether the in vivo change in K(+) and insulin levels might be sufficient to induce reduced abomasal motility. Muscle strips were isolated from the abomasum of slaughtered cows and incubated in buffer solution under isometric conditions. Results show that a decrease in extracellular K(+) (between 5 and 1 mmol/L) or an increase in extracellular insulin concentrations (to 21 mU/L or higher) were able to affect the contraction activity of abomasal muscles. Contraction activity given as median (25th, 75th percentiles) changed from 28.1 mN/min (2.5, 49.9) at 5 mmol/L of K(+) to 9.4 mN/min (0.6, 35.7) at 1 mmol/L of K(+), and from 34.5 mN/min (10.8, 112.4) at 0 mU/L of insulin to 12.0 mN/min (7.6, 49.8) at 120 mU/L of insulin. Because the effect of insulin could be abolished by barium, glybenclamide, or ouabain, the underlying mechanisms of the insulin action could be an increased K(+) conductance or an increased Na/K-ATPase activity or both. Low K(+) or high insulin concentrations both reduced the activity of the circular muscle of the abomasal corpus (i.e., of the part that is responsible for the propulsion of abomasal chymus) and might play an important role in the pathogenesis of abomasal displacement.

Outcome Following Surgical Correction of Abomasal Displacement in Lactating Dairy Cattle: A Retrospective Study of 127 Cases (1999-2010)

“…Numerous predisposing factors and potential etiopathogeneses have been suggested for development of abomasal displacement. Suggested predisposing factors include sex, pregnancy, parity, birth of twins, breed, body size, genotype, season of year, and diet [22][23][24][25][26][27][28][29][30][31].…”

Genome-wide association analysis identifies loci for left-sided displacement of the abomasum in German Holstein cattle

“…Disturbed motility of the abomasum and insufficient transport of gas usually precede LDA (Van Winden and Kuiper, 2003). Causes discussed to be responsible for decreased motility and abomasal atony in cows with LDA are insulin concentration, the effect of the vagus nerve, blood calcium level, potassium homeostasis, and metabolic alkalosis (Van Winden and Kuiper, 2003;Pravettoni et al, 2004;Türck and Leonhard-Marek, 2010). Therefore, candidate genes for LDA might affect insulin metabolism, calcium homeostasis, nerves, neurotransmitters, hormones or their receptors, and other factors that influence gastric motility or digestion.…”

Antidiarrheal Activity of Ethanol Extract of Ophioglossum Vulgatum In Mice And Spasmolytic Effect on Smooth Muscle Contraction of Isolated Jejunum In Rabbits

“…Therefore, we believed that EWOV's antispasmodic effect on the jejunum tract might be related to blocking M receptor and reducing Ca 2+ internal owing. High concentrations of K + can horizontally open voltage-dependent L-type calcium ion channels and allow extracellular Ca 2+ to enter the cell, thereby promoting contraction of intestinal smooth muscle [31,32]. Therefore, the existence of calcium antagonists is suggested as the substance that relaxing the contraction induced by high-K + .…”