Effects of lindane (gamma-hexachlorocyclohexane) on rat heart muscle contraction.

The effects of micromolar concentrations of lindane on the mechanical activity of cardiac left ventricular papillary muscles were studied in adult female rats. Lindane decreased the amplitude and duration of the contraction, and slowed down the time course of its ascending phase (i.e.

Hypericin activates L-type Ca2+ channels in cardiac myocytes.

The effects and the mode of action of hypericin (1) were studied, in the dark, on the action potential (AP) and the L-type Ca2+ channel of frog atrial heart muscle, using intracellular microelectrode and patch-clamp techniques, respectively. In the presence of Ca2+ in Ringer solution, hypericin (1 to 4 microM) did not markedly modify the AP. Total replacement of Ca2+ by Sr2+ in the solution (Ringer Sr2+) revealed that hypericin (4 microM) prolonged the AP duration (APD).

[Second- and third-harmonic generation microscopies for the structural imaging of intact tissues].

One principal advantage of multiphoton excitation microscopy is that it preserves its three-dimensional micrometer resolution when imaging inside light-scattering samples. For that reason two-photon-excited fluorescence microscopy has become an invaluable tool for cellular imaging in intact tissue, with applications in many fields of physiology. This success has driven increasing interest in other forms of nonlinear microscopy that can provide additional information on cells and tissues, such as second- (SHG) and third- (THG) harmonic generation microscopies.

Sensitivity of cardiac background inward rectifying K+ outward current (IK1) to the alkaloids lepadiformines A, B, and C.

Three marine alkaloids, purified from Clavelina moluccensis, were structurally identified as lepadiformines A, B, and C and studied on frog atrial myocytes I(K1), using the patch-clamp technique. Lepadiformine A (0.4 to 3.

Ionic contrast terahertz near-field imaging of axonal water fluxes.

We demonstrate the direct and noninvasive imaging of functional neurons by ionic contrast terahertz near-field microscopy. This technique provides quantitative measurements of ionic concentrations in both the intracellular and extracellular compartments and opens the way to direct noninvasive imaging of neurons during electrical, toxin, or thermal stresses. Furthermore, neuronal activity results from both a precise control of transient variations in ionic conductances and a much less studied water exchange between the extracellular matrix and the intraaxonal compartment.