Table 1.

Passive and active electrical properties of LS bladder neurons in the absence and presence of UTP or UTP and suramin application.

		no UTP (n=39)	UTP (n=21)	UTP+SUR (n=15)
Current Injection	RMP (mV)	−63.9±0.9	−55.6±1.5***	−64.9±2.8††
	Input Resistance (MΩ)	242.0±16.5	224.9±23.0	259.4±17.1
	Rheobase (pA)	142.4±11.6	82.2±5.2**	146.2±16.5††
	AP threshold (mV)	−32.6±0.6	−33.84±1.0	−32.45±1.1
	AP amplitude (mV)	107.3±2.1	101.2±2.6	109.3±4.4
	AP duration (ms)	4.6±0.5	4.7±0.9	4.3±0.9
	AP overshoot (ms)	44.5±1.4	42.0±1.2	46.4±1.8
	AP falling rate (mV/ms)	19.3±1.5	18.6±1.6	20.5±1.9
	AP frequency, 2X rheobase	3.3±0.5	8.7±1.0**	3.1±0.5†††
	Number of cells firing AP induced by UTP	0/39	10/21**	0/15††
ATP (30 μM)	Depolarization (mV)	20.3±2.6	17.6±3.4	na
	Number of APs	1.1±0.4	2.3±0.8	na
αβ-metATP (30 μM)	Depolarization (mV)	13.3±1.7	12.94±1.1	na
	Number of APs	0.8±0.5	1.1±0.6	na

^*P < 0.05;

^**P<0.01;

^***P<0.005 vs. no UTP.

^†P < 0.05;

^††P<0.01;

^†††P<0.005 vs. UTP application.

na, not applicable

Notes: Input resistance was calculated according to the I/V relationship by injecting a series of hyperpolarizing pulses ranging from −300 to 0 pA (30 ms) in 50pA increments. To determine rheobase, a series of 10 ms current pulses in 20pA increments (1s apart) were injected. The maximum current (pA) that did not evoke an action potential was taken as rheobase. Action potential (AP) threshold was determined from the inflection point where membrane potential started to dramatically rise and the phase plot slope (the first derivative of membrane potential, dV/dt) reached 10 mV/ms (Naundorf et al., 2006). AP amplitude was measured from resting membrane potential (RMP) to the peak of the AP, AP overshoot was the amplitude from 0 mV to the peak of the AP, AP duration was determined at 50% of the AP amplitude between the rising and falling phases and the AP falling rate was the velocity of change in potential from the AP peak to RMP.