Erythropoietin increases cytosolic free calcium concentration in vascular smooth muscle cells.
OBJECTIVE
The underlying pathophysiological mechanism leading to raised blood pressure after treatment with erythropoietin is a point of much discussion. Direct vasopressor effects of erythropoietin have been shown recently. The aim was to determine whether erythropoietin effects cytosolic free calcium concentration ([Ca2+]i in vascular smooth muscle cells.


METHODS
The effect of erythropoietin on ([Ca2+]i was measured with the fluorescent dye fura2 in cultured vascular smooth muscle cells from Wistar Kyoto rats.


RESULTS
Mean resting [Ca2+]i was 90.8(SEM 5.6) nM (n = 32). Addition of erythropoietin at concentrations of 100 U.ml-1 and 250 U.ml-1 increased [Ca2+]i to 112.3(5.0) nM (n = 23, p < 0.05) and 128.4(4.0) nM (n = 10, p < 0.01), respectively. Preincubation with erythropoietin caused a dose dependent increase in angiotensin II induced changes of [Ca2+]i in vascular smooth muscle cells.


CONCLUSIONS
One mechanism of erythropoietin induced hypertension may be an increase in [Ca2+]i in vascular smooth muscle cells.
Neusser
M
M
Med Univ-Poliklinik, Münster, Germany.
Tepel
M
M
Zidek
W
W
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004921:Erythropoietin / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY
D004921:Erythropoietin; D002118:Calcium