Calcium sensitivity and cooperativity of permeabilized rat mesenteric lymphatics

Dougherty, Patrick J.; Davis, Michael J.; Zawieja, David C.; Muthuchamy, Mariappan

doi:10.1152/ajpregu.00888.2007

Cited by 39 publications

(36 citation statements)

References 49 publications

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“…Force was measured in intact vessels in response to KCl depolarization (100 mM) or to PE (␣-adrenergic agonist) and diethylamine (DEA)/NO (NO donor) at cumulative concentrations of 1 nM-100 M. A subset of mesenteric arteries was permeabilized with ␣-toxin (1,000 U/ml, Sigma) as previously described (3,43). Vessels were fully relaxed in high relaxing solution (pCa 9) composed of (in mM) 60 potassium methanesulfonate, 5 EGTA, 0.02 CaCl 2, 9.26 MgCl2, 5.2 Na2ATP, 25 creatine phosphate, and 25 N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) with pH 7.1 (intracellular pH) by 1 N KOH based on established protocols (13,37). The dose response to Ca 2ϩ was assessed in mesenteric arteries from pCa 9-pCa 4.5, and force was measured at steady state.…”

Section: Methodsmentioning

confidence: 99%

Redox signaling and splicing dependent change in myosin phosphatase underlie early versus late changes in NO vasodilator reserve in a mouse LPS model of sepsis

Reho

Zheng

Asico

et al. 2015

American Journal of Physiology-Heart and Circulatory Physiology

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Microcirculatory dysfunction may cause tissue malperfusion and progression to organ failure in the later stages of sepsis, but the role of smooth muscle contractile dysfunction is uncertain. Mice were given intraperitoneal LPS, and mesenteric arteries were harvested at 6-h intervals for analyses of gene expression and contractile function by wire myography. Contractile (myosin and actin) and regulatory [myosin light chain kinase and phosphatase subunits (Mypt1, CPI-17)] mRNAs and proteins were decreased in mesenteric arteries at 24 h concordant with reduced force generation to depolarization, Ca(2+), and phenylephrine. Vasodilator sensitivity to DEA/nitric oxide (NO) and cGMP under Ca(2+) clamp were increased at 24 h after LPS concordant with a switch to Mypt1 exon 24- splice variant coding for a leucine zipper (LZ) motif required for PKG-1α activation of myosin phosphatase. This was reproduced by smooth muscle-specific deletion of Mypt1 exon 24, causing a shift to the Mypt1 LZ+ isoform. These mice had significantly lower resting blood pressure than control mice but similar hypotensive responses to LPS. The vasodilator sensitivity of wild-type mice to DEA/NO, but not cGMP, was increased at 6 h after LPS. This was abrogated in mice with a redox dead version of PKG-1α (Cys42Ser). Enhanced vasorelaxation in early endotoxemia is mediated by redox signaling through PKG-1α but in later endotoxemia by myosin phosphatase isoform shifts enhancing sensitivity to NO/cGMP as well as smooth muscle atrophy. Muscle atrophy and modulation may be a novel target to suppress microcirculatory dysfunction; however, inactivation of inducible NO synthase, treatment with the IL-1 antagonist IL-1ra, or early activation of α-adrenergic signaling did not suppressed this response.

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Section: Methodsmentioning

confidence: 99%

Redox signaling and splicing dependent change in myosin phosphatase underlie early versus late changes in NO vasodilator reserve in a mouse LPS model of sepsis

Reho

Zheng

Asico

et al. 2015

American Journal of Physiology-Heart and Circulatory Physiology

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“…Shear stress in collecting vessels was estimated to average Ͻ1 dyn/cm 2 , but throughout normal functioning, peaks of 4 -12 dyn/cm 2 (113) were estimated due to pump-induced fluctuations in flow velocity and diameter. Shear-sensitive pump function of collecting lymphatic vessels is thought to be primarily regulated by shear-modulated nitric oxide release from lymphatic endothelium (60,116,174,373,477), particularly in the valve regions (60). However, when very high lymph flow rates are imposed, pump function decreases and the vessels switch to conduit-like behavior to more efficiently move fluid (373).…”

Section: Lymphatic Functionmentioning

confidence: 99%

Interstitial Fluid and Lymph Formation and Transport: Physiological Regulation and Roles in Inflammation and Cancer

Wiig

Swartz²

2012

Physiological Reviews

575

574

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The interstitium describes the fluid, proteins, solutes, and the extracellular matrix (ECM) that comprise the cellular microenvironment in tissues. Its alterations are fundamental to changes in cell function in inflammation, pathogenesis, and cancer. Interstitial fluid (IF) is created by transcapillary filtration and cleared by lymphatic vessels. Herein we discuss the biophysical, biomechanical, and functional implications of IF in normal and pathological tissue states from both fluid balance and cell function perspectives. We also discuss analysis methods to access IF, which enables quantification of the cellular microenvironment; such methods have demonstrated, for example, that there can be dramatic gradients from tissue to plasma during inflammation and that tumor IF is hypoxic and acidic compared with subcutaneous IF and plasma. Accumulated recent data show that IF and its convection through the interstitium and delivery to the lymph nodes have many and diverse biological effects, including in ECM reorganization, cell migration, and capillary morphogenesis as well as in immunity and peripheral tolerance. This review integrates the biophysical, biomechanical, and biological aspects of interstitial and lymph fluid and its transport in tissue physiology, pathophysiology, and immune regulation.

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“…18 A laparotomy was performed to gain access to the mesenteric lymphatics and loop of small intestine, 3-5 cm long, was gently exteriorized onto a specially designed preparation board. The exposed gut and mesentery were continuously moistened with Dulbecco's phosphate buffer saline (DPBS, Sigma).…”

Section: Tissue Preparationmentioning

confidence: 99%

“…The exposed gut and mesentery were continuously moistened with Dulbecco's phosphate buffer saline (DPBS, Sigma). With the assistance of a stereomicroscope, a suitable unbranched collecting lymphatic vessel (typically 1.7-2.0 mm in length) running along a blood vessel arcade was identified, carefully cleared of connective tissue and fat, 18,19 while being continuously superfused with DPBS. The vessel segment to be studied was then dissected free and transferred to a 35-mm Petri dish containing DPBS.…”

Section: Tissue Preparationmentioning

confidence: 99%

Electrophysiological Properties of Rat Mesenteric Lymphatic Vessels and their Regulation by Stretch

Weid

Lee

Imtiaz

et al. 2014

Lymphatic Research and Biology

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Background: In mammals, lymph is propelled centrally primarily via the phasic contractions of collecting lymphatic vessels, known as lymphatic pumping. Electrophysiological studies conducted in guinea pig and sheep mesenteric lymphatic vessels indicate that contractions are initiated in the lymphatic muscle by nifedipine-sensitive action potentials (APs). Lymphatic pumping is highly sensitive to luminal fluid loading and the mechanical properties of this stretch-induced pumping have been consistently studied, in particular in rat mesenteric lymphatic vessels. However, membrane potential (Vm) and the electrophysiological events underlying stretch-induced lymphatic pumping have not been investigated in the rat. The aim of this study was thus to examine the properties of rat mesenteric lymphatic muscle Vm under resting conditions and to assess changes in Vm caused by distension. Methods and Results: Lymphatic muscle Vm was measured with sharp intracellular microelectrodes either in unstretched conditions or under isometric tension provided by a wire-myograph. In unstretched vessels, Vm was -48 -2 mV (n = 30). APs (amplitude *25 mV) were observed at a frequency of *8/min and were abolished by nifedipine. Under isometric tension, Vm was less polarized (-36 -1 mV, n = 23), even at minimum tension. Increase in tension led to increase in contraction strength and contraction/AP frequency, while Vm was slightly hyperpolarized and AP amplitude not markedly altered. Conclusions: In our experimental conditions, rat lymphatic muscle has electrophysiological characteristics similar to that in other species. It responds to an increase in isometric tension with an increase in AP frequency, but resting Vm is not significantly affected.

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Calcium sensitivity and cooperativity of permeabilized rat mesenteric lymphatics

Abstract: Dougherty PJ, Davis MJ, Zawieja DC, Muthuchamy M. Calcium sensitivity and cooperativity of permeabilized rat mesenteric lymphatics.

Cited by 39 publications

References 49 publications

Redox signaling and splicing dependent change in myosin phosphatase underlie early versus late changes in NO vasodilator reserve in a mouse LPS model of sepsis

Redox signaling and splicing dependent change in myosin phosphatase underlie early versus late changes in NO vasodilator reserve in a mouse LPS model of sepsis

Interstitial Fluid and Lymph Formation and Transport: Physiological Regulation and Roles in Inflammation and Cancer

Electrophysiological Properties of Rat Mesenteric Lymphatic Vessels and their Regulation by Stretch

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