Fig. 4.
Differential effects of mGluR activation by 1S,3R-ACPD on inspiratory synaptic current and baseline membrane current of PMNs. A, Local application of 1S,3R-ACPD (200 μm) decreased inspiratory-modulated synaptic current and induced an inward current when PMN was voltage-clamped at the end-expiratory potential (Vh) of −68 mV. B, Reduction of inspiratory-modulated synaptic current (∼70% of control) at 30 sec after 1S,3R-ACPD (200 μm, local). C, Time course of inspiratory current in response to 1S,3R-ACPD (200 μm, local). Peak inspiratory current is expressed as the percentage of control value. D, E, MCPG blocked 1S,3R-ACPD effects on both synaptic currents and baseline membrane current. Local application of MCPG (5 mm) began 5 min before 1S,3R-ACPD (200 μm, local) application and continued during the course of 1S,3R-ACPD test. F, Summary of effects of 1S,3R-ACPD (200 μm, local) on peak inspiratory-modulated synaptic currents with (n = 8) and without (n = 6) concurrent application of MCPG (5 mm, local). Vertical bars, SEM;asterisk, significant difference (p < 0.05; t test) from control values. Superimposed traces inB and E are the average of six consecutive inspiratory-modulated synaptic currents before and after drug application.