Bradykinin increases intracellular calcium levels in rat testis peritubular cells via the B2 receptor subtype.
1. RT-PCR and Western blots were used to detect bradykinin B(2) receptors in testis and isolated peritubular cells of pre-pubertal rats. RT-PCR demonstrated expression of a single transcript, whereas Western blots showed up to three specific bands that were in accordance with the described native, glycosylated and dimeric form of B(2) receptor proteins, respectively. 2. Fura-2-loaded peritubular cells responded with an instantaneous, linear and transient rise in [Ca(2+)](i) after adding bradykinin. Stimulation of cells with bradykinin concentrations between 1 micro M and 1 pM showed a dose dependent increase of [Ca(2+)](i). The calcium response to bradykinin was diminished after stimulation of peritubular cells in calcium-free buffer. After blocking the SERCA-pumps by thapsigargin and subsequent stimulation with bradykinin, no rise of [Ca(2+)](i) was appreciated. 3. Multiple stimulation of a single peritubular cell by local perfusion with a brief addition of BK (10 nM) resulted in a fast and immediate response. However, the second and third stimuli had slower rise rates and diminished [Ca(2+)](i) peaks, showing desensitization of the kinin receptor. 4. Addition of the bradykinin B(1) receptor agonist [des-Arg(9)]-bradykinin (100 nM) to Fura-2-loaded peritubular cells did not change the [Ca(2+)](i). However, the B(2) receptor antagonist HOE 140 (100 nM) strongly inhibited the bradykinin-induced calcium response. 5. We conclude that the bradykinin-induced increase in [Ca(2+)](i), in testicular peritubular cells is mediated by the stimulation of kinin receptors of the B(2) subtype.
Wennemuth
Gunther
G
Department of Anatomy and Cell Biology, Philipps University, Robert-Koch-Str. 6, D-35037 Marburg, Germany.
Blöcher
Sonja
S
Schill
Wolf-Bernhard
WB
Aumüller
Gerhard
G
Monsees
Thomas K
TK
D000818:Animals; D001920:Bradykinin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D007424:Intracellular Fluid / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000819:agonists* / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin; D001920:Bradykinin; D002118:Calcium