Erythropoietin induced transmembrane calcium influx in essential hypertension.
The effects of erythropoietin (EPO) on cytosolic free calcium concentration ([Ca2+]i) in platelets of 20 essential hypertensive patients (HT) and of 25 normotensive subjects (NT) were investigated using the fura2 technique. In resting platelets [Ca2+]i were not significantly higher in HT compared to NT (74.3 +/- 7.8 nM vs 59.8 +/- 7.0 nM, mean +/- SEM). Addition of EPO significantly increased [Ca2+]i in HT compared to NT (13.8 +/- 5.3 nM vs 0.9 +/- 1.9 nM, p less than 0.01). EPO increased the amount of calcium in intracellular stores. This was confirmed independently using thrombin-induced changes of [Ca2+]i in a calcium-free medium and using chlorotetracycline as a marker of stored calcium. After preincubation with EPO thrombin-induced changes of [Ca2+]i were significantly lower in HT compared to NT (306.1 +/- 30.0 nM vs 407.7 +/- 35.7 nM, p less than 0.05). In a calcium-free medium after preincubation with EPO thrombin-induced changes of [Ca2+]i were significantly lower in HT compared to NT (54.7 +/- 11.8 nM vs 100.9 +/- 10.5 nM, p less than 0.05) indicating lower storage capacity in HT. It is concluded that elevated response to EPO may provide a powerful tool to evaluate diagnosis and underlying pathophysiological mechanisms in essential hypertension.
Tepel
M
M
Med. Univ.-Poliklinik, University of Muenster, Germany.
Wischniowski
H
H
Zidek
W
W
D000328:Adult; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000097:blood*; D002751:Chlortetracycline; D004921:Erythropoietin / Q000494:pharmacology*; D005260:Female; D016257:Fura-2; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D011994:Recombinant Proteins / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology
D011994:Recombinant Proteins; D004921:Erythropoietin; D013917:Thrombin; D002118:Calcium; D016257:Fura-2; D002751:Chlortetracycline