A Clockwork Hypothesis: Synaptic Release by Rod Photoreceptors Must Be Regular

From: Biophysical Journal | Date: December 1, 2005| Author: Ahmad, Kareem M; Schein, Stan | Copyright information

ABSTRACT

We can see at light intensities much lower than an average of one photon per rod photoreceptor, demonstrating that rods must be able to transmit a signal after absorption of a single photon. However, activation of one rhodopsin molecule (Rh*) hyperpolarizes a mammalian rod by just 1 mV. Based on the properties of the voltage-dependent Ca^sup 2+^ channel and data on [Ca^sup 2+^] in the rod synaptic terminal, the 1 mV hyperpolarization should reduce the rate of release of quanta...

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