Northern blot analysis of K+channel transcripts in postnatal rat cerebellum in vivo.A, Poly(A)-enriched RNA was isolated from rat pup cerebella at P2, P4, P6, P7, P8, P10, P14, and P21 and screened by Northern blot analysis with 32P-labeled antisense probes for rslo (mslo probe, region S9–S10) and Kv3.1 (full-length probe) sequences. A 4.4 kb band detected by themslo probe was increased in signal intensity at day 7 and thereafter. A 5.5 kb band detected by the Kv3.1 probe was present at all stages. Constitutively expressed cyclophilin (cyclo; 0.6 kb) served as a standard for the amount of RNA loaded in each lane. All bands inlanes P2 and P4 appeared to run slightly faster than those in other lanes; ladders run on both sides of the sample lanes showed a comparable difference. The shifted positions were taken into account when analyzing signals at P2 and P4.B, Densitometric analysis of the Northern blot provided an estimate of relative intensities of the rslo and Kv3.1 signals after subtraction of adjacent background and standardization to the signal for cyclophilin. Signal intensities are calculated as a percentage of the signal measured at postnatal day 2 (the first time point assayed) and plotted as a function of developmental age of the rat cerebellum.
