Table 3.

ATPase activity in the presence of 2 mM concentrations of various nucleotides.

	ATPase activity (% of control)
Nucleotide	Triphosphate	Diphosphate	Monophosphate
Adenosine	100	72.6 ± 16.7	-9.2 ± 9.3
Guanosine	120.8 ± 19.6	55.4 ± 17.1	N.D.
Cytosine	64.2 ± 7.6	N.D.	N.D.
Uridine	101.4 ± 55.0	N.D.	N.D.

ATPase activity of isolated D10 plasma membranes tested without nucleotide and absorbance due to the nucleotide hydrolysis was subtracted. Values are means of three separate experiments, each performed in quadruplicate ± standard deviations and are expressed as % of control in presence of ATP. N.D.: not determined.