Caffeine has been shown to increase the Ca(2+) release frequency (Ca(2+) sparks) from the sarcoplasmic reticulum (SR) through ryanodine-sensitive stores and relax gastric fundus smooth muscle. Increased Ca(2+) store refilling increases the frequency of Ca(2+) release events and store refilling is enhanced by CaM kinase II (CaMKII) phosphorylation of phospholamban (PLB). These findings suggest that transient, localized Ca(2+) release events from the SR may activate CaMKII and contribute to relaxation by enhancing store refilling due to PLB Thr17 phosphorylation. To investigate this possibility, we examined the effects of caffeine on CaMKII, muscle tone, and PLB phosphorylation in murine gastric fundus smooth muscle. Caffeine (1 mM) hyperpolarized and relaxed murine gastric fundus smooth muscle and activated CaMKII. Ryanodine, tetracaine, or cyclopiazonic acid each prevented CaMKII activation and significantly inhibited caffeine-induced relaxation. The large-conductance Ca(2+)-activated K(+) channel blocker iberiotoxin, but not apamin, partially inhibited caffeine-induced relaxation. Caffeine-induced CaMKII activation increased PLB Thr17, but not PLB Ser16 phosphorylation. 3-Isobutyl-1-methylxanthine increased PLB Ser16 phosphorylation, but not PLB Thr17 phosphorylation. The CaMKII inhibitor KN-93 inhibited caffeine-induced relaxation and PLB Thr17 phosphorylation. These results show that caffeine-induced CaMKII activation and PLB phosphorylation play a role in the relaxation of gastric fundus smooth muscles.

ObjectiveTo assess the intrarater and interrater reliability of the supraspinatus thickness measured by ultrasonography (US) in normal subjects and to identify the relationship between the supraspinatus thickness measured by US and cross sectional area (CSA) of the supraspinatus muscle by magnetic resonance imaging (MRI) in hemiplegic patients.MethodWe examined 20 shoulders of normal subjects and 10 shoulders of hemiplegic patients. In normal subjects, one examiner measured the supraspinatus thickness twice by US at the scapular notch and another examiner measured the supraspinatus thickness several days later. The intrarater and interrater reliability of supraspinatus thickness measurements were then evaluated. In hemiplegic patients, the supraspinatus thickness at the scapular notch was measured by US in affected side and compared with CSA of the supraspinatus muscle at the scapular notch and the Y-view of MRI.ResultsOne examiner's supraspinatus thickness measurement average was 1.72±0.21 cm and 1.74±0.24 cm, and the other examiner's supraspinatus thickness measurement average was 1.74±0.22 cm in normal subjects. Intraclass correlation coefficients of intrarater and interrater examination were 0.91 and 0.88, respectively. For hemiplegic patients, the supraspinatus thickness measured by US was 1.66±0.13 cm and CSA by MRI was 4.83±0.88 cm2 at the Y-view and 5.61±1.19 cm2 at the scapular notch. The Pearson Correlation Coefficient between the supraspinatus thickness at the scapular notch and the CSA at the Y-view was 0.72 and that between the supraspinatus thickness and CSA at the scapular notch was 0.76.ConclusionThe supraspinatus thickness measurement by US is a reliable method and is positively correlated with the CSA of the supraspinatus muscle in MRI in hemiplegic patients. Therefore, supraspinatus thickness measurement by US can be used in the evaluation of muscle atrophy and to determine therapeutic effects in hemiplegic patients.

The mechanisms by which nitric oxide (NO) relaxes smooth muscles are unclear. The NO donor sodium nitroprusside (SNP) has been reported to increase the Ca2+ release frequency (Ca2+ sparks) through ryanodine receptors (RyRs) and activate spontaneous transient outward currents (STOCs), resulting in smooth muscle relaxation. Our findings that caffeine relaxes and hyperpolarizes murine gastric fundus smooth muscles and increases phospholamban (PLB) phosphorylation by Ca2+/calmodulin (CaM)-dependent protein kinase II (CaM kinase II) suggest that PLB phosphorylation by CaM kinase II participates in smooth muscle relaxation by increasing sarcoplasmic reticulum (SR) Ca2+ uptake and the frequencies of SR Ca2+ release events and STOCs. Thus, in the present study, we investigated the roles of CaM kinase II and PLB in SNP-induced relaxation of murine gastric fundus smooth muscles. SNP hyperpolarized and relaxed gastric fundus circular smooth muscles and activated CaM kinase II. SNP-induced CaM kinase II activation was prevented by KN-93. Ryanodine, tetracaine, 2-aminoethoxydiphenylborate, and cyclopiazonic acid inhibited SNP-induced fundus smooth muscle relaxation and CaM kinase II activation. The Ca2+-activated K+ channel blockers iberiotoxin and apamin inhibited SNP-induced hyperpolarization and relaxation. The soluble guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo-[4,3-alpha]quinoxalin-1-one inhibited SNP-induced relaxation and CaM kinase II activation. The membrane-permeable cGMP analog 8-bromo-cGMP relaxed gastric fundus smooth muscles and activated CaM kinase II. SNP increased phosphorylation of PLB at Ser16 and Thr17. Thr17 phosphorylation of PLB was inhibited by cyclopiazonic acid and KN-93. Ser16 and Thr17 phosphorylation of PLB was sensitive to 1H-[1,2,4]oxadiazolo-[4,3-alpha]quinoxalin-1-one. These results demonstrate a novel pathway linking the NO-soluble guanylyl cyclase-cGMP pathway, SR Ca2+ release, PLB, and CaM kinase II to relaxation in gastric fundus smooth muscles.

Spinal epidural hematoma is a rare but serious neurological complication of neuraxial anesthesia. Enoxaparin sodium is a low molecular weight heparin (LMWH) for use in preventing deep venous thrombosis in patients undergoing total hip arthroplasty and total knee arthroplasty. Hemorrhage is an uncommon but documented adverse reaction when using LMWH. We report a case of epidural hematoma after lumbar epidural anesthesia in a patient who administered enoxaparin in perioperative period.

We investigated intracellular Ca2+ waves, spontaneous transient outward currents (STOCs), and membrane potentials of gastric antrum smooth muscle cells from wild-type and phospholamban-knockout mice. The NO donor sodium nitroprusside (SNP) increased intracellular Ca 2+ wave activity in wild-type antrum smooth muscle cells, but had no effect on the constitutively elevated intracellular Ca 2+ wave activity of phospholamban-knockout cells. STOC activity was also constitutively elevated in phospholamban-knockout antrum smooth muscle cells relative to wild-type cells. SNP or 8-bromo-cGMP increased the STOC activity of wild-type antrum smooth muscle cells, but had no effect on STOC activity of phospholamban-knockout cells. Iberiotoxin, but not apamin, inhibited STOC activity in wild-type and phospholamban-knockout antrum smooth muscle cells. In the presence of SNP, STOC activity in wild-type and phospholamban-knockout antrum smooth muscle cells was inhibited by ryanodine, but not 2-APB. The cGMP-dependent protein kinase inhibitor KT5823 reversed the increase in STOC activity evoked by SNP in wild-type antrum smooth muscle cells, but had no effect on STOC activity in phospholamban-knockout cells. The resting membrane potential of phospholamban-knockout antrum smooth muscle cells was hyperpolarized by approximately −6 mV compared to wild-type cells. SNP hyperpolarized the resting membrane potential of wild-type antrum smooth muscle cells to a greater extent than phospholamban-knockout antrum smooth muscles. Despite the hyperpolarized membrane potential, slow wave activity was significantly increased in phospholamban-knockout antrum smooth muscles compared to wild-type smooth muscles. These results suggest that phospholamban is an important component of the mechanisms regulating the electrical properties of gastric antrum smooth muscles.