The pattern of expression of mRNA for all adenylyl cyclase isoforms in myometrium has not been previously described. One study, using the relatively insensitive technique of Northern blotting, identified mRNA for adenylyl cyclase isoforms II and IV in uteri from late-gestation rats. Messenger RNA for the other isoforms of adenylyl cyclase were not identified, nor was the cell of origin of mRNA for isoforms II and IV. Results of the present study, using the more sensitive technique of RT-PCR, show that myometrium expresses mRNA for adenylyl cyclase isoforms II-IX. We did not identify mRNA for adenylyl cyclase isoform I despite obtaining PCR products from the rat brain using primers based on bovine sequence. This suggests that these adenylyl cyclase type I primers, which were designed on the basis of bovine sequence, do anneal to rat adenylyl cyclase cDNA. The lack of a PCR product with the use of identical primers in rat myometrial cells suggests that this isoform is not expressed in myometrial cells. buy diabetes drugs
While the expression of adenylyl cyclase type I is generally limited to neural tissues, the mRNA encoding several adenylyl cyclase isoforms is widely expressed in peripheral tissues. The ability to detect the mRNA expression of a given isoform is dependent upon the sensitivity of the technique used. While RT-PCR may detect the expression of a particular isoform, it is unknown whether or not this very sensitive technique may detect the expression of low-abundance mRNAs that do not result in the synthesis of a biologically significant amount of protein. Adenylyl cyclases type IV, V, VI, and VII showed wide tissue expression as detected by RT-PCR. Adenylyl cyclases type V and IX were detected by RNase protection in a wide variety of peripheral tissues, while Northern blotting showed expression of types VI and VII in many peripheral tissues.