Table 1.

Dependence of downstream calcium fluorescence response upon stimulus duration and location

	Amplitude	Rise Time, s	Response Time, s	Area
	Stimulus duration
Duration, ms
100	0.00 ± 0.00*	0.00 ± 0.00*	0.00 ± 0.00*	0.3 ± 0.16‡
250	1.00 ± 0.18*	0.15 ± 0.02*	0.29 ± 0.06*	3.6 ± 0.85‡
500	1.65 ± 0.04†	0.27 ± 0.03†	0.59 ± 0.06*	9.1 ± 0.91*
1000	1.68 ± 0.04†	0.31 ± 0.05†	1.09 ± 0.09*	14.8 ± 1.65*
	Stimulus proximity
Location
Adjacent	1.60 ± 0.06	0.22 ± 0.02	0.64 ± 0.07	8.4 ± 1.20
Inside	1.65 ± 0.07	0.21 ± 0.02	0.76 ± 0.09	10.5 ± 1.81
30 μm	0.00 ± 0.00§	0.00 ± 0.00§	0.00 ± 0.00§	0.1 ± 0.11§

Summary data are means ± SE. Respective data sets were obtained from the same vessels (n = 8). Calcium fluorescence responses were initiated by an ACh stimulus, and measurements were taken 500 μm downstream of the stimulus site. For stimulus duration, the ACh micropipette was positioned immediately adjacent to the arteriolar wall and ejection current was held constant at 500 nA. As the duration of the ACh stimulus was varied, fluorescence increased with pulse duration. Amplitude, rise time, decay, and area under the curve were calculated as described in methods. For stimulus location, the ACh stimulus was held constant (500 nA, 500-ms pulse duration) and the location of the ACh micropipette was varied. Downstream calcium fluorescence responses were observed only when the tip of the micropipette was immediately adjacent to the arteriole or within its lumen. Values for amplitude and area are arbitrary fluorescence units. For stimulus duration:

^*significantly different from other pulse durations (P < 0.05);

^†significantly different from 100 and 250 ms (P < 0.05);

^‡significantly different from 500 and 1000 ms (P < 0.05). For stimulus location:

^§significantly different from other proximities (P < 0.05).