1. Potassium currents were studied under voltage‐clamp conditions in nerve cell bodies of the nudibranch Tritonia diomedia. 2. could be separated into three distinct components on basis their sensitivity to 4‐aminopyridine (4‐AP), tetraethyl‐ammonium (TEA) and Co2+ Mn2+ ions. 3. A transient potassium current, similar fast outward current described by Connor & Stevens (1971b) Neher (1971), was blocked externally applied 4‐AP but much less sensitive TEA or Mn2+. single ion binds each...

1. Inactivation of delayed outward current was studied by voltage clamp isolated neurone somata the molluscs Archidoris and Anisodoris. During prolonged steps in normal artificial sea water rises to a peak then declines non-zero steady-state. repetitive pulses at repetition rates slower than 2/sec, amplitude second pulse is commonly less end preceding pulse, giving impression continued inactivation during repolarized interval. We have termed this property cumulative inactivation. 2. Two...

The blocking action of 4-aminopyridine (4-AP) and 3, 4-diaminopyridine (Di-AP) on transient potassium current (IA) in molluscan central neurons was studied internal perfusion voltage-clamp experiments. Identical effects were seen when the drugs applied either externally or internally. It found that aminopyridines have two kinds IA channels. first involves block open channels during depolarizing pulses results a shortening time to peak an increase initial rate decay current. This effect drug...

1. Action potentials recorded from isolated dorid neurone somata increase in duration, i.e. broaden, during low frequency repetitive firing. Spike broadening is substantially reduced by external Co ions and implicates an inward Ca current. 2. During voltage clamp steps at frequencies slower than 1 Hz, 100 mM‐tetraethyl ammonium (TEA) currents do not amplitude. 3. Repetitive action result inactivation of delayed outward Likewise, which cause current also longer duration potentials. 4. The...

1. Spikes in molluscan bursting cells are followed by depolarizing afterpotentials (DAPs) which not seen nonbursting the same ganglia. DAPs from successive spikes sum to provide a drive capable of sustaining multiple discharge. 2. Subthreshold depolarization activates DAP-like process bursters. 3. DAP amplitude increases as cell is hyperpolarized beyond potassium equilibrium potential. The changed intracellular iontophoresis TEA-Cl. reduced 39% after 10-min exposure CA++-free saline, and 66%...

In many eukaryotic cell types, receptor activation leads to the formation of inositol 1,4,5-trisphosphate (IP3) which causes calcium ions (Ca) be released from internal stores. Ca release was observed in response muscarinic agonist carbachol by fura-2 imaging N1E-115 neuroblastoma cells. followed after a latency 0.4 20 s. Latency not caused feedback on IP3 receptors, but rather accumulation threshold for release. The dependence dose fitted model synthesis and degradation compete, resulting...

Forskolin, a diterpene extracted from Coleus forskolii, stimulates the production of cAMP in variety cells and is potentially an important tool for studying role modulation neuronal excitability. We studied effects forskolin on neurons nudibranch molluscs found that it caused characteristic, reversible changes amplitude waveform transient K current, IA, also activated inward current similar to cAMP-dependent previously described molluscan neurons. Forskolin altered time course IA activation...

Bluefin tuna have a unique physiology. Elevated metabolic rates coupled with heat exchangers enable bluefin tunas to conserve in their locomotory muscle, viscera, eyes and brain, yet hearts operate at ambient water temperature. This arrangement of warm fish cold heart is among vertebrates can result reduction cardiac function the despite elevated demands endothermic tissues. In this study, we used laser scanning confocal microscopy electron investigate how acute chronic temperature change...

Calcium entry into molluscan neurones during depolarizing voltage‐clamp steps activates an outward current which on repolarization decays over periods of more than 30 sec. This slowly decaying tail was used to study the relation between calcium buffering in cytoplasm and decline a calcium‐activated membrane process. Calcium‐dependent also studied after injection cytoplasm. The time course fall much less sensitive amplitude amount entry. Increasing bath temperature from 5 15 degrees C...

The peptide L-phenylalanyl-L-methionyl-L-arginyl-L-phenylalaninamide (FMRF-amide) was pressure-applied onto the somata of bursting neurons L4 and L6 in Aplysia abdominal ganglion. FMRF-amide causes a biphasic response, first depolarizing then hyperpolarizing neuron. In voltage-clamp experiments, induces an inward current that begins 100-200 msec after applying peaks 2-10 sec. This is followed by outward with latency 2-5 sec 15-65 entire response lasts 1-5 min. Experiments were done to...

Multiple Sclerosis (MS) is a degenerative disease with symptoms that include irregulation of body temperature, fatigue, depression and often excessive yawning. Fatigue an ongoing issue for many people MS there little understood about the mechanisms involved in regulating temperature after activity. Measuring monitoring fatigue has been reported healthy subjects but no reports to date have considered thermoregulation using E-textile specialist wearable garments MS. Discussion thermoregulatory...

The activation of muscarinic receptors in N1E-115 neuroblastoma cells elicits a voltage-independent calcium current. current turns on slowly, reaches its maximum value approximately 45 s after applying the agonist, is sustained as long agonist present, and recovers by one half 10 washing away. density 0.11 +/- 0.08 pA/pF (mean SD; n = 12). It absent zero-Ca++ saline reduced Mn++ Ba++. I(V) curve characterizing has an extrapolated reversal potential > +40 mV. observed heavily loaded...

SUMMARY Box jellyfish, or cubomedusae (class Cubozoa), are unique among the Cnidaria in possessing lens eyes similar morphology to those of vertebrates and cephalopods. Although these were described over 100 years ago, there has been no work done on their electrophysiological responses light. We used an electroretinogram (ERG) technique measure spectral sensitivity Caribbean species Tripedalia cystophora. The have two kinds eyes, lower upper eyes. found that both eye types sensitivities,...

SUMMARY The nudibranch mollusc Melibe leonina swims by bending from side to side. We have identified a network of neurons that appears constitute the central pattern generator (CPG) for this locomotor behavior, one only few such networks be described in cellular detail. consists two pairs interneurons, termed `swim interneuron 1' (sint1) and`swim 2' (sint2), arranged around plane bilateral symmetry. Interneurons on brain, which includes paired cerebral, pleural and pedal ganglia, coordinate...

In many types of eukaryotic cells, the activation surface receptors leads to production inositol 1,4,5-trisphosphate and calcium release from intracellular stores. Calcium can occur in complex spatial patterns, including waves that traverse cytoplasm. Fluorescence video microscopy was used view single mouse neuroblastoma cells. The propagation slowed by buffers bind quickly, such as BAPTA, but not a buffer with slower on-rate, EGTA. This shows key feedback event wave is rapid diffusion...

The spatial distribution of Ca current in molluscan neuron cell bodies was studied using a large patch method combination with 2- microelectrode voltage clamp. has resolution equal to about 0.1% the body area. is not uniformly distributed. density varies between patches, changing by as much factor 2.5 over distance 20 micron, and there evidence that occurs “hot spots” involving few hundred channels. increases moderately steep gradient from soma cap, opposite axon, toward axon hillock....

Fura 2 imaging was used to measure intracellular Ca2+ signals in N1E-115 mouse neuroblastoma cells during combined activation of bradykinin (BK) and cholinergic receptors. BK carbachol (CCh) both activate phospholipase C (PLC) cause release from inositol 1,4,5-trisphosphate (IP3)-sensitive stores. The signal response CCh is prolonged by the influx, but does not appear influx pathway. When are applied together (BK+CCh), composed influx. also activated BK+CCh a subset that respond with...

1. Membrane ionic currents in bursting pace‐maker neurones of the marine mollusc Tritonia were studied voltage‐clamp experiments with emphasis on slow tail current relaxations after depolarizing pulses. 2. The undergoes a complex transition from an initially inward to outward as duration pulse is lengthened. It was found that sum two separate and independent currents. Methods devised study each isolation. 3. A current, termed IB, activated by depolarization decays exponentially return ‐55 mV...

The relationship between the depletion of IP3-releasable intracellular Ca2+ stores and activation Ca(2+)-selective membrane current was determined during stimulation M1 muscarinic receptors in N1E-115 neuroblastoma cells. External is required for refilling voltage-independent, receptor-regulated represents a significant source refilling. time course store measured with fura-2 fluorescence imaging, it compared nystatin patch voltage clamp. At maximum density (0.18 + .03 pA/pF; n = 48),...

The stimulation of IP3 production by muscarinic agonists causes both intracellular Ca2+ release and activation a voltage-independent cation current in differentiated N1E-115 cells, neuroblastoma cell line derived from mouse sympathetic ganglia. Earlier work showed that the membrane requires an increase 3′,5′-cyclic guanosine monophosphate (cGMP) produced through NO-synthase/guanylyl cyclase cascade suggested cells may express cyclic nucleotide–gated ion channels. This was tested using patch...

Muscarinic agonists elicit large increases in intracellular Ca2+ and guanosine 3',5'-cyclic monophosphate (cGMP) N1E-115 neuroblastoma cells. Both signals are blocked cells loaded with the buffer 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid showing that increase concentration ([Ca2+]i) is necessary to stimulate cGMP accumulation. Inhibition of nitric oxide synthase (NOS) blocks response without affecting peak amplitude signal, it concluded Ca(2+)-dependent activation NOS required...

Recovery from K current inactivation was studied in molluscan neurons using two-microelectrode and internal perfusion voltage clamps. Experiments were designed to study the voltage-dependent delayed outward (IK) without contamination other currents. The amount of recovery rate increase dramatically when membrane potential is made more negative. time course at resting potential, -40 mV, well fit by a single exponential with constant 24.5 s (n = 7). At negative voltages, best sum two...