Abstract: The effects of monovalent cation K+, Na+ and divalent cation Mg2+, Ca2+ (all of these are in choloride) and ATP on the swelling and contraction of isolated mung bean mitochondria have been described. These cations and ATP show different effects in different test medium K+, Na+ initiated a rapid and instantaneous swelling of mung bean mitochondria in hypotonic medium. The degree of swelling decreased with the increase of concentration of KC1 or NaCl. ATP and Mg2+ can initiate a contraction of the swelling mitochondria in hypotonic medium but there was no effect on the swelling mitochondria in isotonic or hypertonic medium (0.125 mol/l or 0.6 mol/l KCl or NaCI). The degree of swelling in KCl is more than that one in NaCI at the same concentration. Mg2+, Ca2+ at physiological concentration (2 mmol/l MgCl2 1 mmol/l CaCl2) initiated a slower and a greater degree swelling of mung bean mitochondria in hypotonic medium. 5 mmol/l ATP initiated a part of contraction of the swelling mitochondria. 1 mmol/l Ca++ initiated a very small swelling of mung bean mitochondria in 0.125 mmol/l KC1 or 0.25 mol/l mannitol. 5 mmol/l ATP greatly promoted the swelling. 10 mmol/l MgCl2 initiated a part of contraction of the swelling. 2 mmol/l MgCl2 initiated an obivious swelling in 0.25 mol/l mannitol. 5 mmol/l ATP promoted the swelling, 10 mmol/l MgCl2 initiated a part of contraction of the swelling mitochondria. 2 mmol/l MgCl2, 0.125 mol/1 KC1, 0.25 mol/1 mannitol all together, which can not initiated any swelling of nmng bean mitochondria but 5 mmol/l ATP greatly promoted the swelling in this condition. The patterns of mung bean mitochondria in different condition have been observed.

Key words: Mung bean mitochondria, Swelling and contraction, Cation, ATP