Table 5

Homologous desensitization IP3 responses in cells with low numbers of TxA₂ receptors^a

Low Receptor Number	IP3 (% Increase above Control)		Response in Cells Pretreated with Vehicle (%)
Low Receptor Number	Pretreated with vehicle	Pretreated with U46619	Response in Cells Pretreated with Vehicle (%)
Wild type (n = 7)	86 ± 12	43 ± 10^†	48 ± 12
Mutant (n = 5)	39 ± 11^*	32 ± 9	81 ± 7^*

5-a Cells were pretreated for 10 min with 10 μM U46619, washed and then rechallenged with 10 μM U46619 as described under “Materials and Methods.” Experiments were performed in duplicate,n = the number of experiments. * P < .05versus the wild type by unpaired t test, † P < .025 versus vehicle-treated cells by pairedt test.