1. Previous electrophysiological studies have suggested the presence of KCa and Kv channels in human platelets. However, the pharmacology of these channels has not been defined. 2. We have studied potassium channels in human platelets by measuring the efflux of 86Rb+ (a marker for K+) from 86Rb(+)-loaded cells, and have defined their responses to stimulation by the platelet agonist thrombin and...

The importance of heparan- and chondroitin-sulfate proteoglycans in physiological and pathological processes led to the investigation of the regulation of beta1,3-glucuronosyltransferase I (GlcAT-I), responsible for the completion of glycosaminoglycan-protein linkage tetrasaccharide, a key step prior to polymerization of chondroitin- and heparan-sulfate chains. We have cloned and functionally c...

Human Jurkat T cells containing a stably integrated human T cell leukaemia virus type 1 (HTLV-1) long terminal repeat (LTR) reporter gene construct were used to study the role of calcium-dependent cellular activation pathways in LTR trans-activation. Treatment of these cells with the calcium ionophore ionomycin resulted in a reduced basal response of the LTR and reduced responses to 12-O-tetrad...

We previously reported an enhanced peak response of intracellular free Ca to thrombin in platelets of spontaneously hypertensive rats in comparison with normotensive Wistar-Kyoto rats. In the present study, we compared the platelet intracellular Ca response to the receptor-linked agonist thrombin with the response to the Ca ionophore ionomycin. Basal intracellular Ca was higher in hypertensive ...

This study investigated the presence of cell membrane docking proteins synaptosomal-associated protein, 25 and 23 kD (SNAP-25 and SNAP-23) in satellite glial cells (SGCs) of rat trigeminal ganglion; whether cultured SGCs would release glutamate in a time- and calcium-dependent manner following calcium-ionophore ionomycin stimulation; and if botulinum neurotoxin type A (BoNTA), in a dose-depende...

Immunological analysis using monoclonal antibodies against subspecies of protein kinase C revealed the predominant expression of the isozyme, type II, in human megakaryoblastic leukemic cells. We investigated the effects of phorbol diester 12-O-tetradecanoyl phorbol-13-acetate (TPA), the Ca2+ ionophore ionomycin and synthetic diacylglycerol 1-oleoyl-2-acetylglycerol (OAG) on the immunocytochemi...

The successful outcome of intracytoplasmic sperm injection (ICSI) with round-headed spermatozoa (globozoospermia) and ionomycin assisted activation oocytes is reported. A 30-year-old man with 100% globozoospermia underwent ICSI treatment. Real-time Polymerase Chain Reaction (PCR) detection indicates that the patient was DPY19L2 homozygous deletion. Nine metaphase II oocytes were injected with r...

Tight control of lung liquid (LL) regulation is vital for pulmonary function. The aim of this work was to determine whether PKC activation is involved in the physiological regulation of LL volume in a whole lung preparation. Rat lungs were perfused with a modified Ringer solution, and the lumen was filled with the same solution without glucose. LL volume was measured during a control period and...

Aggregation of marine sponge cells (Microciona prolifera) resembles stimulus-response coupling of higher organisms in which activation of protein kinase C and movements of intracellular Ca provide twin signals. We now report that activators of protein kinase C (phorbol esters) and ionomycin act synergistically to aggregate sponge cells. Surprisingly--since extracellular Ca is required for integ...