Ion channels that are gated in response to membrane deformation or "stretch" are empirically designated stretch-activated channels. Here we describe a stretch-activated nonselective cation channel in the basolateral membrane (BLM) of the proximal tubule (PT) that is nucleotide sensitive. Single channels were studied in cell-intact and cell-free patches from the BLM of PT cells that maintain their epithelial polarity. The limiting inward Cs⁺ conductance is ~28 pS, and channel activity persists after excision into a Ca²⁺- and ATP-free bath. The stretch-dose response is sigmoidal, with half-maximal activation of about 19 mmHg at 40 mV, and the channel is activated by depolarization. The inward conductance sequence is: NH ~ Cs⁺ ~ Rb⁺ > K⁺ ~ Na⁺ ~ Li⁺ > Ca²⁺ ~ Ba²⁺ > N-methyl-D-glucamine ~ tetraethylammonium. The venom of the common Chilean tarantula, Grammostola spatulata, completely blocks channel activity in cell-attached patches. Hypotonic swelling reversibly activates the channel. Intracellular ATP concentration ([ATP]_i) reversibly blocks the channel (inhibitory constant ~0.48 mM), suggesting that channel function is coupled to the metabolic state of the cell. We conclude that this channel may function as a Ca²⁺ entry pathway and/or be involved in regulation of cell volume. We speculate this channel may be important when [ATP]_i is depleted, as occurs during periods of increased transepithelial transport or with ischemic injury.