Table 3.

The effect of 4-AP on plasma catecholamine concentrations.

Treatment	WKY		SHR
	Norepinephrine (nM)	Epinephrine (nM)	Norepinephrine (nM)	Epinephrine (nM)
PBS + PBS (time-control)	0.5 ± 0.1	8.1 ± 1.5	1.2 ± 0.2**	13.2 ± 2.5
PBS + 4-AP (control)	2.0 ± 0.2†††	9.5 ± 1.5	10.2 ± 1.5***,†††	16.1 ± 4.6
Scopolamine + 4-AP			12.0 ± 1.7	18.8 ± 4.0
Right vagal n. stimulation + 4-AP	4.2 ± 0.7‡‡	19.3 ± 4.2‡	11.2 ± 1.6	44.1 ± 14.1‡
Nadolol + 4-AP	1.8 ± 0.3	9.0 ± 0.9	11.2 ± 1.6	47.3 ± 19.1‡‡
Atropine + nadolol + 4-AP	2.6 ± 0.4	13.6 ± 2.5	12.3 ± 1.5	43.1 ± 7.1‡‡
SR59230A + 4-AP	3.3 ± 0.5	6.1 ± 0.9	9.1 ± 2.0	16.7 ± 5.0

Comparisons were made between the WKY and SHR time-controls or 4-AP-controls, between the time-controls and PBS + 4-AP-controls (†), and between the PBS + 4-AP-controls and corresponding experimental groups (‡). Plasma from 12 rats were included in the PBS + 4-AP control groups, and five to seven rats in the other groups. *,‡ – P ≤ 0.05, **,‡‡ – P ≤ 0.01, ***,††† – P ≤ 0.001.