The field EPSP recorded in the CA1 region of rat hippocampal slices is potentiated by bath application of the direct adenylate cyclase activator forskolin (Chavez-Noriega and Stevens, 1992a). We have now used the whole-cell patch-clamp technique to analyze the effect of forskolin on evoked synaptic currents and on spontaneous and miniature excitatory postsynaptic currents (sEPSCs and mEPSCs) re...

Substances known to alter cyclic nucleotide levels in cells were applied to the isolated toad retina and effects on rod electrical and adaptive behavior were studied. The retina was continually superfused in control ringer's or ringer's containing one or a combination of drugs, and rod activity was recorded intracellularly. Superfusion with cGMP, Bu(2)GMP, isobutylmethylxanthine (IBMX; a phosph...

The influence of cyclic AMP on cartilage degradation was investigated by using phosphodiesterase inhibitors [theophylline and 3-isobutyl-1-methylxanthine (IBMX)], forskolin (which activates the catalytic subunit of adenylate cyclase) and cyclic AMP analogues (dibutyryl and 8-bromo). Breakdown was assessed by quantification of proteoglycans released into the media of 8-day bovine nasal-septum ca...

introduction: to evaluate the camp -mediated ibmx (3-isobutyle -1-methyl xanthin) and db-camp (dibutyryl camp) effects on differentiation of human embryonic stem cells (hescs) into nerve cells were the objectives of this study. methods: we have used royan h1 hesc- derived embryoid bodies with four treatment groups: six days treatment with ibmx (5×10 -4m) and db-camp (10 -9m) (referred to as cam...

Phosphodiesterases (PDEs) are critical regulators of cyclic nucleotides in the heart. In ventricular myocytes, the L-type Ca(2+) current (I(Ca,L)) is a major target of regulation by PDEs, particularly members of the PDE2, PDE3 and PDE4 families. Conversely, much less is known about the roles of PDE2, PDE3 and PDE4 in the regulation of action potential (AP) properties and I(Ca,L) in the sinoatri...

Transepithelial [(14)C]urea fluxes were measured across cultured Madin-Darby canine kidney (MDCK) cells permanently transfected to express the urea transport protein UT-A1. The urea fluxes were typically increased from a basal rate of 2 to 10 and 25 nmol.cm(-2).min(-1) in the presence of vasopressin and forskolin, respectively. Flux activation consisted of a rapid-onset component of small ampli...

Serotonin (5-HT) has multiple physiological actions at lobster neuromuscular junctions, including facilitation of transmitter release from nerve terminals and an increase in the tone and excitability of muscle fibers. These physiological effects of 5-HT are accompanied by a rise in intracellular levels of cAMP. We have used combined biochemical and physiological approaches to investigate whethe...

The microfilament lattice, composed primarily of filamentous (F)-actin, determines in large part the mechanical (deformability) properties of neutrophils, and thus may regulate the ability of neutrophils to transit a microvascular bed. Circulating factors may stimulate the neutrophil to become rigid and therefore be retained in the capillaries. We hypothesized that cell stiffening might be atte...

The actions of the phosphodiesterase inhibitor denbufylline on the excitability of hippocampal neurons were investigated by means of extracellular and intracellular recordings. Denbufylline, which has been shown to selectively inhibit a low KM, Ca/+/calmodulin-inde pendent phosphodiesterase isozyme, concentration-dependently increased the amplitude of the extracellularly recorded CA1 population...

We have previously demonstrated that tetramethylpyrazine (TMP) could stimulate colonic and pancreatic anion secretion. The present study investigated the signaling pathways and cellular mechanisms underlying the effect of TMP using human colonic Caco-2 cells, with permeabilized apical or basolateral membranes, in conjunction with Ussing chamber technique, intracellular cAMP and Ca2+ measurement...