TABLE 3.

The effect of the α5 subunit on receptor desensitization

The receptors were activated by 1 mM ACh or 100 μM nicotine. The desensitization time courses were examined with respect to 100 to 50% of peak (or 80% for nicotine) decay time and the residual current levels at the end of the 30-s application. The data are mean ± S.D. from five to eight cells. All estimates are from traces started within 30 s of entering the whole-cell configuration. The statistical analysis applies to comparison with the data from the α3β4 and α3β4α5 receptors.

Agonist and Receptor	Decay Time		Residual Current
	100-to-50%	100-to-80%
	s		%
ACh
α3β4	15 ± 12		29 ± 23
α3β4α5	13 ± 6†		25 ± 14†,†
α3β4α5(Asn398)	17 ± 3†,†		29 ± 7†
Nicotine
α3β4		0.9 ± 0.6	9 ± 3
α3β4α5		8.6 ± 6.2*	50 ± 25**
α3β4α5(Asn398)		9.6 ± 3.7***,†	48 ± 15***,†

^† Not significant.

^* P < 0.05.

^** P < 0.01.

^*** P < 0.001.