A vibrating microelectrode, or vibrating probe (Jaffe and Nuccitelli, 1974), was used to map the pattern of artificially created electric currents flowing around single muscle fibers at the edge of frog cutaneous pectoris muscles. When a muscle fiber was impaled with a micropipette, a "point sink" of current was often created at the site of impalement because of injury to the cell membrane. Cur...

Vasopressin increases the net transport of sodium across the isolated urinary bladder of the toad by increasing the mobility of sodium ion within the tissue. This change is reflected in a decreased DC resistance of the bladder; identification of the permeability barrier which is affected localizes the site of action of vasopressin on sodium transport. Cells of the epithelial layer were impaled ...

Investigation of the identity and modes of action of neurotransmitters in the mammalian central nervous system can be facilitated by simultaneous intracellular recording of membrane potential and extracellular iontophoresis of agonists and antagonists. We describe here techniques for conveniently constructing a compound microelectrode, originally described by Sonnhof (Pflugers Arch 341, 351-358...

The heads of demembranated spermatozoa of the sea urchin Tripneustes gratilla, reactivated at different concentrations of ATP, were held by suction in the tip of a micropipette and vibrated laterally with respect to the head axis. This imposed vibration resulted in a stable rhythmic beating of the reactivated flagella that was synchronized to the frequency of the micropipette. The reactivated f...

The electrical potential profile of the isolated toad bladder was examined in the spontaneously active, chronically short-circuited, and intermittently short-circuited states by means of glass micropipettes. The position of the micropipette tip within the bladder was evaluated by measuring the D.C. resistance between the micropipette tip and the reference electrode on the serosal side of the bl...

PURPOSE We previously demonstrated liver- and lobe-selective gene transfer following instillation of plasmid DNA (pDNA) onto the liver surface in mice. Safety concerns must be resolved prior to future clinical use. Thus, we investigated safety of liver surface instillation of pDNA in normal and hepatitis mice. METHODS pDNA was instilled onto the liver surface in normal and carbon tetrachlorid...

The formal transfer potentials of hydrophilic alkali metal ions Li(+), Na(+), K(+), Rb(+), and Cs(+) were determined at water|room temperature ionic liquid (w|RTIL) interfaces. A working curve for an interface held at the tip of a micropipette (25 μm in diameter) was developed through simulated cyclic voltammograms (CVs) via finite element analysis with Comsol Multiphysics software. This method...