Table 1.

Effects of phenoxybenzamine on responses to noradrenaline, neuronal and extraneuronal uptake of [³H]-noradrenaline in the cat's nictitating membrane

Groups Phenoxybenzamine (g/ml)	n	Responses to (–) NA Max. PBA Max. cont. (1)	n	Endogenous content (μg NA/g) (2)	Neuronal uptake (ng [3H]-NA/μg NA) (3)	n	Extraneuronal uptake (ng [3H]-NA/g) (4)
Controls	32	0·96 ± 0·04	18	9·08 ± 0·98	22·5 ± 1·6	17	137·0 ± 12·0
10−8	7	0·82 ± 0·07	12	8·65 ± 1·80	33·7 ± 3·3*	—	—
10−7	7	0·71 ± 0·04	16	7·38 ± 0·80	22·2 ± 2·3	—	—
0·3 × 10−6	—	—	4	10·10 ± 2·32	29·2 ± 3·5	—	—
10−6	6	0–26 10–03	6	11–864 1–56	9–3 ± 1·0*	7	171·0 ± 19·0
10−5	4	002 ± 001	4	15–12+1–13*	l-6 ± 0·3†	6	54·3 ± 3·4†

(1) Ratio between the maximum development of tension obtained with (—) noradrenaline in the presence of phenoxybenzamine PBA and the maximum in the controls. (2) Endogenous noradrenaline was measured fluorometrically in the muscles of the nictitating membrane. (3) Neuronal uptake expressed as ng[³H]-noradrenaline taken up per μg of endogenous noradrenaline. (4) Extraneuronal uptake was determined in chronically denervated muscles in which monoamine oxidase and catechol-O-methyl transferase were inhibited. Results are mean values ± s.e. of the mean. Variance analysis was applied to the groups (see Methods), n = number of experiments

^*P<0·05

^†P<0·01.