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Biomedical subjects

D T Frazier

Publications and source records attributed to D T Frazier.

At least 73 records · Page 4Linked to original sources
PubMed1972

The action of phospholipases on the inner and outer surface of the squid giant axon membrane.

1. The effects of phospholipases on resting potential, action potential and membrane ionic conductances of squid giant axons have been studied by means of internal perfusion and voltage clamp techniques. The sample of phospholipases used exhibited both phospholipase A and B activities.2. When applied externally, phospholipases had no effect on the resting and action potentials at a concentration of 100 mug/ml.3. When applied internally, the enzymes effectively suppressed the amplitude and maximum rate of rise of the action potential at a concentration of 100 mug/ml. The resting potential started decreasing appreciably only after the action potential had been suppressed to a considerable extent.4. Under voltage clamp conditions, the peak transient current was suppressed following internal perfusion of phospholipases, 150 mug/ml. The steady-state current began to decrease, and the leakage current to increase only after the transient current had been suppressed to a considerable extent.5. The time course of sodium inactivation was not significantly slowed by internal perfusion of the enzymes.6. The curve relating the peak transient conductance to the membrane potential was shifted in the direction of depolarization after internal perfusion of phospholipases. No appreciable shift of the steady-state conductance curve was observed.7. These experimental results are discussed in connexion with the possible role of membrane phospholipids in the conductance changes associated with excitation.

Action Potentials↗
PubMed1969

Hemicholinium-3: noncholinergic effects on squid axons.

Hemicholinium-3, when applied to the inside of a squid axon, is effective in blocking the action potential. This action is not antagonized by the addition of choline or acetylcholine to the perfusate. Voltage-clamp experiments show that hemicholinium-3 depresses both the early transient and late steady-state components of membrane ionic conductances, with a greater effect on the peak transient component.

Acetylcholine↗