Figure 7. Semi-quantitative assessment of hypoxic regulation of ET-1, ETA-, and ETB-receptor mRNA transcript levels in human isolated islets. RNA from isolated human islets incubated at either normoxic (21% O2) or hypoxic (1% O2) culture conditions for 24 and 48 h was reversed transcribed and amplified with specific intron-spanning primers for either ET-1, ETA-, or ETB-receptor. PCR cycle numbers were chosen to guarantee linear amplification. Amplification of the housekeeping gene beta-actin served for normalization.