Table 1.

Serotonin and hormone data

Parameter and Group	Basal Period	Experimental Period
		P1	P2	P3	P4
Arterial blood 5-HT, mg/l
SAL	0.9±0.2	0.8±0.2	0.8±0.2	0.8±0.2	0.7±0.2
HTP	1.0±0.2	1.0±0.2	1.1±0.2	1.3±0.3	2.0±0.6*
Net hepatic 5-HT balance, μg·kg−1·min−1
SAL	2.2±0.5	1.7±1.0	0.4±1.5	−0.1±2.2	1.2±1.4
HTP	−2.8±2.9	−3.3±1.9	−4.0±1.8	−2.8±3.1	−7.4±3.4*
Arterial plasma insulin, pmol/l
SAL	46±8	108±18	110±11	129±13	135±17
HTP	27±3	120±9	123±11	143±11	155±6
Hepatic sinusoidal insulin, pmol/l
SAL	128±21	417±67	425±45	399±47	414±37
HTP	181±15	411±34	359±39	383±44	386±40
Arterial plasma glucagon, ng/l
SAL	46±7	41±5	38±5	38±4	35±8
HTP	33±4	39±4	28±3	32±3	34±2
Hepatic sinusoidal glucagon, ng/l
SAL	54±8	58±8	56±5	52±5	48±4
HTP	45±7	44±4	42±4	47±4	42±5
Arterial plasma cortisol, nmol/l
SAL	74±24	64±18	55±14	43±10	62±10
HTP	82±21	66±12	51±12	72±33	116±43
Arterial plasma norepinephrine, pg/ml
SAL	185±39	154±33	152±52	177±39	173±44
HTP	114±38	139±59	115±57	140±65	142±49
Arterial plasma epinephrine, pg/ml
SAL	149±55	78±33	55±14	74±33	75±39
HTP	102±43	93±39	79±43	112±55	61±38

Values are means ± SE. 5-HT, 5-hydroxytryptamine. SAL dogs (n = 7) received intraportal saline infusion during periods 1–4 (P1–P4); HTP dogs (n = 6) received saline during P1 and intraportal 5-hydroxytryptophan (5-HTP) at 10, 20, and 40 μg·kg⁻¹·min⁻¹, respectively, during P2–P4. Negative values indicate net hepatic uptake.

^*P < 0.05 vs. SAL.