Coxal Muscle Receptors in the Crab: the Receptor Potentials of S and T Fibres in Response to Ramp Stretches

• DOI: 10.1242/jeb.55.3.813
• Publication Date: 2021-04-25T15:06:26Z
• Authors: B. M. H. Bush; Alan Roberts
• Keywords: Receptor potential; Stretch receptor; Hysteresis; Sensory receptor

ABSTRACT Intracellular and extracellular recordings from the two large-diameter S T sensory fibres of posterior thoracico-coxal muscle receptor in shore crabs confirm graded, dynamic-static nature potentials evoked by stretching muscle, lack afferent impulses. Slow ramp-function stretches evoke with characteristic shapes, which differ between several respects: The dynamic component fibre resembles an algebraic sum length velocity responses a variable initial ‘acceleration’ (?) transient, while it commonly declines (‘adapts’) during stretching, especially at greater velocities starting lengths. On release stretch usually exhibits ‘negative response’, but repolarizes rapidly often slight hyperpolarization. response is generally than that fibre, increases more steeply approximately logarithmically over 10- to 50-fold range. The’ static ‘or degree depolarization fairly linearly very non-linearly fibre. displays pronounced hysteresis its increasing decreasing lengths, shows little hysteresis. not small rapid oscillations or ‘noise’ superimposed upon strongly depolarized ‘static’ potentials. may be affected reciprocally some forms contraction. Graded ‘D’ non-muscular depressor-receptor strand coxo-basal joint show Receptor respond motor nerve stimulation spontaneous impulses thoracic ganglion slow, facilitating summating excitatory junctional mechanisms underlying differences responses, their functional significance animal, are discussed, comparisons drawn other receptors.