TABLE 6.

IC₂₅–IC₇₅ intervals, describing the concentration needed to increase inhibition of phosphodiesterase-5 (PDE5), phosphodiesterase-3 (PDE3), and inhibition of cAMP- and cGMP-efflux from 25% to 75%, at temperatures ranging from 37°C to 20°C.

IC25–IC75	PDE5		PDE3		cGMP-efflux		cAMP-efflux
Temperature	Sildenafil (μM)	Vardenafil (μM)	Sildenafil (μM)	Vardenafil (μM)	Sildenafil (μM)	Vardenafil (μM)	Sildenafil (μM)	Vardenafil (μM)
37°C	0.038 ± 0.000	0.059 ± 0.029	460 ± 38.8	61.0 ± 14.3	23.6 ± 9.08	12.6 ± 3.89	27.1 ± 9.36	30.9 ± 6.82
34°C	0.055 ± 0.004	0.028 ± 0.012	411 ± 40.4	72.1 ± 3.24	13.5 ± 1.74	19.2 ± 3.16	19.8 ± 1.82	19.9 ± 0.967
32°C	0.060 ± 0.006	0.062 ± 0.016	485 ± 32.4	107 ± 27.0	9.76 ± 3.99	18.0 ± 4.12	20.0 ± 4.27	27.3 ± 6.19
28°C	0.083 ± 0.008	0.049 ± 0.016	450 ± 35.9	128 ± 35.9	12.0 ± 1.96	10.6 ± 2.75	13.8 ± 3.85	17.3 ± 6.59
24°C	0.098 ± 0.012*	0.074 ± 0.005	584 ± 55.0	148 ± 31.9	11.4 ± 4.73	13.0 ± 1.74	−	−
20°C	0.132 ± 0.048*	0.103 ± 0.027	697 ± 22.5*	709 ± 105*	19.2 ± 8.45	28.1 ± 14.6	−	−

Values are mean ± SEM given in μM. *Significant difference (P-value < 0.05) when compared to normothermic control. Neither of the drugs inhibited cAMP-efflux below 28°C.