KNG1 and familial hypocalciuric hypercalcemia: We also observed an enhanced 5-HT-mediated contraction in FHH rats in the presence of either BK or Kv channel inhibitors, which is consistent with the observation that greater BK and/or Kv channel activity contributes to diminished 5-HT-mediated vasoconstrictor response in FHH rats (Fig. 8).