γ-Rays-generated ROS induce apoptosis via mitochondrial and cell cycle alteration in smooth muscle cells.

Purpose: γ-rays (IR) cause an increase in intracellular calcium [Ca(2+)], alters contractility and triggers apoptosis via the activation of protein kinase C in intestinal guinea pig smooth muscle cells. The present study investigated the role of the mitochondria in these processes and characterized proteins involved in IR-induced apoptosis.

Materials And Methods: Intestinal smooth muscle cells were exposed to 10-50 Gy from a (60)Co γ-source.

Changes in intracellular Ca2+ levels induced by cytokines and P2 agonists differentially modulate proliferation or commitment with macrophage differentiation in murine hematopoietic cells.

The role of intracellular Ca2+ (Ca2+i) on hematopoiesis was investigated in long term bone marrow cultures using cytokines and agonists of P2 receptors. Cytokines interleukin 3 and granulocyte/macrophage colony stimulator factor promoted a modest increase in Ca2+i concentration ([Ca2+]i) with activation of phospholipase Cgamma, MEK1/2, and Ca2+/calmodulin kinase II. Involvement of protein kinase C was restricted to stimulation with interleukin 3.

Gamma-radiation induces apoptosis via sarcoplasmatic reticulum in guinea pig ileum smooth muscle cells.

We investigated the effects of gamma-radiation on cells isolated from the longitudinal smooth muscle layer of the guinea pig ileum, a relatively radioresistant tissue. Single doses (up to 50 Gy) reduced the amount of sarcoplasmatic reticulum and condensed the myofibrils, as shown by electron microscopy 3 days post-irradiation. After that, contractility of smooth muscle strips was reduced.

alpha- and epsilon-protein kinase C activity during smooth muscle cell apoptosis in response to gamma-radiation.

The use of gamma-radiation in treatment of pelvic cancer is associated with injury of healthy surrounding tissues and disorders of intestinal motility; however, the cellular mechanisms involved are unclear. We tested the hypothesis that exposure of visceral smooth muscle cells (SMCs) to gamma-radiation induces apoptosis via activation of specific protein kinase C (PKC) isoforms. Cultured SMCs and slices from guinea pig ileum smooth muscle longitudinal layer (GPISMLL) were exposed to 10 to 50 Gy.

Effects of arachnotoxin on intracellular pH and calcium in human spermatozoa.

Objective: To determine the effect of arachnotoxin (ATx), a venom extracted from the Chilean spider Latrodectus mactans, on intracellular calcium ([Ca(2+)](i)) and pH (pH(i)) in capacitated human spermatozoa.

Design: Spermatozoa were collected from fertile adult men (n = 8). Mobile spermatozoa were collected by the "swim up" technique and stimulated with the crude extract of ATx and with progesterone (P).

Activation of P2Y1 receptor triggers two calcium signaling pathways in bone marrow erythroblasts.

In this study, we describe the presence of P2 receptor subtypes and Ca2+ signaling in erythroblasts. ATP and ADP produced a biphasic increase of intracellular Ca2+ concentration ([Ca2+]i), with an initial transient phase followed by a sustained phase. Reverse transcription polymerase chain reaction (RT-PCR) showed the expression of P2Y1, P2Y2 and P2Y12.

Heparin and heparan sulfate disaccharides bind to the exchanger inhibitor peptide region of Na+/Ca2+ exchanger and reduce the cytosolic calcium of smooth muscle cell lines. Requirement of C4-C5 unsaturation and 1--> 4 glycosidic linkage for activity.

Heparin and heparan sulfate fragments, obtained by bacterial heparinase and heparitinases, bearing an unsaturation at C4-C5 of the uronic acid moiety, are able to produce up to 80% reduction of the cytosolic calcium of smooth muscle cell lines. Unsaturated disaccharides from chondroitin sulfate, dermatan sulfate, and hyaluronic acid are inactive, indicating that, besides the unsaturation of the uronic acid, a vicinal 1 --> 4 glycosidic linkage is needed. An inverse correlation between the molecular weight and activity is observed.