Recombinant human thyrotropin enhances endothelial-mediated vasodilation of conduit arteries.
BACKGROUND
Endothelial cells possess receptors to TSH. Their role is largely unknown.


OBJECTIVE
The objective of the study was to determine whether elevated serum TSH levels, as occur in hypothyroidism, affect endothelial function of large arteries and vascular risk biomarkers.


METHODS
Thirty-four consecutively recruited patients, who had undergone thyroidectomy for thyroid carcinoma, were studied in connection with one of the monitoring procedures based on recombinant human (rh) TSH administration. Flow-mediated dilation (FMD) of the brachial artery and serum vascular risk markers were measured at baseline and for 5 d after the administration of rhTSH (0.9 mg im on d 1 and 2). Holter electrocardiogram and echocardiography were performed on d 2.


RESULTS
rhTSH caused a rapid increase in flow-mediated dilation from the basal value of 10.2 to 15.6% at 6 h (P < 0.0000001), to 16.1% on d 2 (P < 0.0000001), and to 14.9% on d 6 (P = 0.0015). The results were identical when the analysis was made in a subgroup of 19 patients free of vascular risk conditions. Vascular cell adhesion molecule-1, TNFalpha, IL-6, and high sensitive C-reactive protein were unaffected by rhTSH, whereas homocysteine was decreased. Arterial blood pressure, mean 24-h heart rate, and left ventricular function were unaffected by rhTSH.


CONCLUSIONS
rhTSH causes marked and persistent activation of the endothelial mediated vasodilation, independent of systemic hemodynamic changes.
Napoli
Raffaele
R
Department of Internal Medicine and Cardiovascular Sciences, University Federico II, 80131 Naples, Italy. napoli@unina.it.
Apuzzi
Valentina
V
Bosso
Giorgio
G
D'Anna
Carolina
C
De Sena
Antonietta
A
Pirozzi
Concetta
C
Marano
Aldo
A
Lupoli
Gelsy Arianna
GA
Cudemo
Giuseppe
G
Oliviero
Ugo
U
Matarazzo
Margherita
M
Lupoli
Giovanni
G
Saccá
Luigi
L
D001916:Brachial Artery / Q000187:drug effects / Q000502:physiology; D004562:Electrocardiography / Q000187:drug effects; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000494:pharmacology; D013972:Thyrotropin / Q000097:blood / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*
D011994:Recombinant Proteins; D013972:Thyrotropin