[Diagnostic utility of creatine kinase elevation in the routine biochemical profile in cats]

INTRODUCTION

Creatine kinase (CK) is a muscle enzyme that is very sensitive to muscle damage. Therefore, serum CK is measured particularly to confirm suspected myopathy. Since 2013, this enzyme has been included in the routine chemistry profile in our hospital. Soon thereafter, the subjective impression developed that its elevation did not correlate to and was not explainable with the actual clinical problem. Therefore, the aim of this retrospective study was to investigate in which clinical cases the CK elevation was adequate and in which cases without clinical evidence of muscle damage the CK was so markedly elevated that it implied a clinically relevant muscle damage. For this purpose, we evaluated the CK values of 1641 cats presented in the years 2013/2014 at our university animal hospital. The CK was comprehensibly elevated in cats with trauma and various diseases with obvious and traceable muscle damage like thrombo-embolic damage or seizures. In addition, the CK was elevated in diseases where concomitant muscle damage is perceivable like in cats with hypertrophic cardiomyopathy. However, the CK also was commonly and sometimes dramatically elevated in cats of essentially any disease group without any comprehensible skeletal muscular lesion. These results confirm the hypothesis that the diagnostic value of this parameter is most questionable. A CK elevation does not allow any conclusion regarding its original diagnostic purpose, i.e. to confirm the presence of a clinically relevant myopathy.

Characterization of the peristaltic reflex in murine distal colon

Ascending and descending neuromuscular reflexes play an important role in gastrointestinal motility. However, the underlying mechanisms in colon are incompletely understood. Nerve stimulation (NS)- and balloon distention (BD)-mediated reflexes in distal colonic circular smooth muscle (CSM) and longitudinal smooth muscle (LSM) of mice were investigated using conventional intracellular recordings. In the CSM, NS evoked ascending purinergic inhibitory junction potentials (IJPs), whereas BD induced atropine-sensitive ascending depolarization with superimposed action potentials (APs). The ascending depolarization reached a peak ∼4-7 s after the onset of distention and gradually returned to baseline after termination of the distention. In the LSM, NS produced an ascending biphasic IJP followed by a train of atropine-sensitive APs. Both stimuli produced similar descending IJPs in CSM and LSM, which were blocked by MRS-2500 and MRS-2179, putative purinergic receptor blockers. These data indicate that in the murine distal colon, descending purinergic inhibition in both CSM and LSM occurs. Ascending responses are more complex, with NS producing both inhibition and excitation to CSM and LSM, and BD evoking only cholinergic excitation.

Effect of oxidative stress on Rho kinase II and smooth muscle contraction in rat stomach

Recent studies have shown that both Rho kinase signaling and oxidative stress are involved in the pathogenesis of a number of human diseases, such as diabetes mellitus, hypertension, and atherosclerosis. However, very little is known about the effect of oxidative stress on the gastrointestinal (GI) smooth muscle Rho kinase pathway. The aim of the current study was to investigate the effect of oxidative stress on Rho kinase II and muscle contraction in rat stomach. The peroxynitrite donor 3-morpholinosydnonimine (SIN-1), hydrogen peroxide (H2O2), and peroxynitrite were used to induce oxidative stress. Rho kinase II expression and ACh-induced activity were measured in control and oxidant-treated cells via specifically designed enzyme-linked immunosorbent assay (ELISA) and activity assay kits, respectively. Single smooth muscle cell contraction was measured via scanning micrometry in the presence or absence of the Rho kinase blocker, Y-27632 dihydrochloride. All oxidant agents significantly increased ACh-induced Rho kinase II activity without affecting its expression level. Most important, oxidative stress induced by all three agents augmented ACh-stimulated muscle cell contraction, which was significantly inhibited by Y-27632. In conclusion, oxidative stress activates Rho kinase II and enhances contraction in rat gastric muscle, suggesting an important role in GI motility disorders associated with oxidative stress.