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Polyps of the gallbladder are often incidentally identified during radiographic evaluation of abdominal pain. Once identified, they pose a dilemma with respect to their proper long-term management. Herein, polyps of the gallbladder are reviewed with specific attention to their management in light of their malignant potential. The available data suggest that polyps larger than 10 mm or that show rapid growth should be considered suggestive of malignancy, prompting cholecystectomy.

The potassium channel blocker, 4-aminopyridine (4-AP), stimulates neurotransmitter release via plasma membrane depolarization and subsequent activation of voltage-gated calcium channels. The present study assessed the effects of 4-AP on intracellular calcium levels in the human neuroblastoma cell line CHP-100. Blockade of K+ channels with 4-AP significantly increased intracellular calcium concentration ([Ca2+]i). This increase occurred via activation of plasma membrane Ca2+ channels. The 4-AP induced rise in [Ca2+]i was not inhibited by the L-type Ca2+ channel blocker nifedipine but was sensitive to the N-type Ca2+ channel blocker omega-contotoxin GVIA. Tetrodotoxin did not alter the effect of 4-AP. These results suggest that in CHP-100 cells, following inhibition of K+ channels by 4-AP, N-type Ca2+ channels are activated.