Reciprocal regulation of Ca²+-activated outward K+ channels of Pyrus pyrifolia pollen by heme and carbon monoxide.

• The regulation of plant potassium (K+) channels has been extensively studied in various systems. However, the mechanism of their regulation in the pollen tube is unclear. • In this study, the effects of heme and carbon monoxide (CO) on the outward K+ (K+(out)) channel in pear (Pyrus pyrifolia) pollen tube protoplasts were characterized using a patch-clamp technique. • Heme (1 µM) decreased the probability of K+(out) channel opening without affecting the unitary conductance, but this inhibition disappeared when heme was co-applied with 10 µM intracellular free Ca²+. Conversely, exposure to heme in the presence of NADPH increased channel activity. However, with tin protoporphyrin IX treatment, which inhibits hemeoxygenase activity, the inhibition of the K+(out) channel by heme occurred even in the presence of NADPH. CO, a product of heme catabolism by hemeoxygenase, activates the K+(out) channel in pollen tube protoplasts in a dose-dependent manner. The current induced by CO was inhibited by the K+ channel inhibitor tetraethylammonium. • These data indicate a role of heme and CO in reciprocal regulation of the K+(out) channel in pear pollen tubes.

Impacts of yishen jiangzhuo granule on B lymphocytes and regulatory T-lymphocytes in patients with chronic renal insufficiency / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To explore the impacts of Yishen Jiangzhuo Granule (YJG) on peripheral blood B-cells and regulatory T-cells (Treg) in patients with chronic renal insufficiency (CRI).</p><p><b>METHODS</b>Fifty-three CRI patients were randomly assigned to two groups, the control group and the YJG group. Before and after treatment, the following parameters in blood were detected: the peripheral Treg, percentage (CD19+), activation rate (CD19+ CD69+) and apoptotic rate (AV) of B-lymphocyte by flow cytometry; cytokines (IL-6 and IL-10) by CBA stream protein analyzing system; high sensitivity C-reactive protein (hs-CRP) by scattering turbidimetric analysis; homocysteine (Hcy) by end-point method; hemoglobin (HGB) content by Beckman-Coulter hemo-analyser; blood contents of Ca, phosphate (P), blood urea nitrogen (BUN), creatinine (SCr) and plasma albumin (Alb) by automatic biochemical analyser; and urinary contents of creatinine (UCr) by inverse HPLC. Then the product of calcium-phosphate (Ca x P) was calculated based on blood contents of Ca2 and P and the clearance rate of endogenous creatinine (CCr) was calculated based on blood BUN and SCr.</p><p><b>RESULTS</b>After treatment CD19+ and CCr significantly increased (P < 0.01), but AV and SCr decreased in both groups (P < 0.01), with the changes in the YJG group were more significant than those in the control group (P < 0.05); levels of CD19+ CD69+, Treg, IL-6, IL-10, CRP, BUN, P and Ca x P showed no significant change (P > 0.05); levels of Ca2+, HGB and Alb increased as well as of Hcy in both groups (P < 0.05). Correlation analysis: There were negative correlation in CD19+ with AV and Hcy; Alb with AV and Hcy; CCr with CRP, SCr and BUN, while positive correlation existed in SCr with CRP and BUN; and CRP with BUN.</p><p><b>CONCLUSIONS</b>YJG can improve renal function, and delay the progress of renal failure, and it also shows the regulatory effect on B lymphocytes by lowering the apoptosis rate and improving the percentage of CD19+ in patients.</p>

Identification of hyperpolarization-activated calcium channels in apical pollen tubes of Pyrus pyrifolia.

The pollen tube has been widely used to study the mechanisms underlying polarized tip growth in plants. A steep tip-to-base gradient of free cytosolic calcium ([Ca(2+)](cyt)) is essential for pollen-tube growth. Local Ca(2+) influx mediated by Ca(2+)-permeable channels plays a key role in maintaining this [Ca(2+)](cyt) gradient. Here, we developed a protocol for successful isolation of spheroplasts from pollen tubes of Pyrus pyrifolia and identified a hyperpolarization-activated cation channel using the patch-clamp technique. We showed that the cation channel conductance displayed a strong selectivity for divalent cations, with a relative permeability sequence of barium (Ba(2+)) approximately Ca(2+) > magnesium (Mg(2+)) > strontium (Sr(2+)) > manganese (Mn(2+)). This channel conductance was selective for Ca(2+) over chlorine (Cl(-)) (relative permeability P(Ca)/P(Cl) = 14 in 10 mm extracellular Ca(2+)). We also showed that the channel was inhibited by the Ca(2+) channel blockers lanthanum (La(3+)) and gadolinium (Gd(3+)). Furthermore, channel activity depended on extracellular pH and pollen viability. We propose that the Ca(2+)-permeable channel is likely to play a role in mediating Ca(2+) influx into the growing pollen tubes to maintain the [Ca(2+)](cyt) gradient.

Ca2+ influx into lily pollen grains through a hyperpolarization-activated Ca2+-permeable channel which can be regulated by extracellular CaM.

Confocal laser scanning microscopy (CLSM) and whole-cell patch-clamp were used to investigate the role of Ca2+ influx in maintaining the cytosolic Ca2+ concentration ([Ca2+]c) and the features of the Ca2+ influx pathway in germinating pollen grains of Lilium davidii D. [Ca2+]c decreased when Ca2+ influx was inhibited by EGTA or Ca2+ channel blockers. A hyperpolarization-activated Ca2+-permeable channel, which can be suppressed by trivalent cations, verapamil, nifedipine or diltiazem, was identified on the plasma membrane of pollen protoplasts with whole-cell patch-clamp recording. Calmodulin (CaM) antiserum and W7-agarose, both of which are cell-impermeable CaM antagonists, lead to a [Ca2+]c decrease, while exogenous purified CaM triggers a transient increase of [Ca2+]c and also remarkably activated the hyperpolarization-activated Ca2+ conductance on plasma membrane of pollen protoplasts in a dose-dependent manner. Both the increase of [Ca2+]c and the activation of Ca2+ conductance which were induced by exogenous CaM were inhibited by EGTA or Ca2+ channel blockers. This primary evidence showed the presence of a voltage-dependent Ca2+-permeable channel, whose activity may be regulated by extracellular CaM, in pollen cells.