Interactions between sodium balance, intrarenal dopamine synthesis, and sympathetic activity in HLA-identical kidney donors and recipients.
Intrarenal dopamine (DA) synthesis, sympathetic activity and sodium homeostasis were studied in eight HLA-identical kidney recipient and donor pairs at 50, 150, and 300 mmol sodium intake. Trimethaphan was given intravenously (i.v.), to mimic acute denervation, tyramine i.v. to induce noradrenaline (NE) release, and the DA precursor DOPA i.v. to study DOPA to DA conversion. Blood pressure was higher in the recipients (P < 0.05) and was not influenced by sodium intake. Cumulative sodium balances were not different between the groups. Sodium intake did not affect DA excretion in either group. The recipients had higher DA (P < 0.05) and DOPA (P < 0.01) excretions and lower urinary DA over DOPA ratio (UDA/DOPA, P < 0.01) and lower NE excretion (P < 0.05) during the whole study. High sodium intake suppressed the UDA/DOPA in both groups (P < 0.05). Trimetaphan decreased renal vascular resistance (RVR) and increased sodium excretion only in the donors (P < 0.05), while GFR increased in both groups. During HiSo tyramine increased RVR in the recipients (P < 0.01) and UDA/DOPA in the donors (P < 0.05). DOPA infusion increased DA excretion four to fivefold but did not change sodium excretion in either group. It is concluded that the recipients maintained sodium homeostasis well but seem to have an impaired functional innervation of the transplanted kidney. NE release seem to stimulate intrarenal DOPA to DA conversion. In both groups a direct relation between DA and sodium excretion was lacking.
Barendregt
J N
JN
Department of Nephrology, University Hospital Leiden, The Netherlands.
van Nispen tot Pannerden
L L
LL
Chang
P C
PC
D000328:Adult; D001340:Autonomic Nerve Block; D001794:Blood Pressure; D004295:Dihydroxyphenylalanine / Q000008:administration & dosage; D004298:Dopamine / Q000096:biosynthesis*; D005260:Female; D006680:HLA Antigens / Q000276:immunology*; D006706:Homeostasis; D006801:Humans; D007668:Kidney / Q000294:innervation / Q000378:metabolism*; D016030:Kidney Transplantation / Q000276:immunology*; D008297:Male; D012964:Sodium / Q000378:metabolism*; D012982:Sodium, Dietary / Q000008:administration & dosage; D013564:Sympathetic Nervous System / Q000502:physiology*; D014019:Tissue Donors; D014294:Trimethaphan / Q000008:administration & dosage; D014439:Tyramine / Q000008:administration & dosage
D006680:HLA Antigens; D012982:Sodium, Dietary; D004295:Dihydroxyphenylalanine; D014294:Trimethaphan; D012964:Sodium; D004298:Dopamine; D014439:Tyramine