Yarowsky P J, Krueger B K, Olson C E, Clevinger E C, Koos R D
Department of Pharmacology and Experimental Therapeutics, University of Maryland School of Medicine, Baltimore 21201.
Proc Natl Acad Sci U S A. 1991 Nov 1;88(21):9453-7. doi: 10.1073/pnas.88.21.9453.
The expression of mRNAs coding for the alpha subunit of rat brain and rat heart sodium channels has been studied in adult and neonatal rat cerebral cortex using the reverse transcription-polymerase chain reaction (RT-PCR). Rat brain sodium channel subtype I, II, IIA, and III sequences were simultaneously amplified in the same PCR using a single oligonucleotide primer pair matched to all four subtype sequences. Identification of each subtype-specific product was inferred from the appearance of unique fragments when the product was digested with specific restriction enzymes. By using this RT-PCR method, products arising from mRNAs for all four brain sodium channel subtypes were identified in RNA extracted from adult rat cerebral cortex. The predominant component was type IIA with lesser levels of types I, II, and III. In contrast, the type II and IIA sequences were the predominant RT-PCR products in neonatal rat cortex, with slightly lower levels of type III and undetectable levels of type I. Thus, from neonate to adult, type II mRNA levels decrease relative to type IIA levels. Using a similar approach, we detected mRNA coding for the rat heart sodium channel in neonatal and adult rat cerebral cortex and in adult rat heart. These results reveal that mRNAs coding for the heart sodium channel and all four previously sequenced rat brain sodium channel subtypes are expressed in cerebral cortex and that type II and IIA channels may be differentially regulated during development.
利用逆转录聚合酶链反应（RT-PCR），在成年和新生大鼠的大脑皮层中研究了编码大鼠脑和大鼠心脏钠通道α亚基的mRNA的表达情况。在同一PCR反应中，使用与所有四种亚型序列匹配的单一寡核苷酸引物对，同时扩增大鼠脑钠通道亚型I、II、IIA和III的序列。当产物用特定限制性酶消化时，通过独特片段的出现推断出每种亚型特异性产物。通过这种RT-PCR方法，在从成年大鼠大脑皮层提取的RNA中鉴定出了所有四种脑钠通道亚型的mRNA产生的产物。主要成分是IIA型，I型、II型和III型的水平较低。相比之下，II型和IIA型序列是新生大鼠皮层中主要的RT-PCR产物，III型水平略低，I型未检测到。因此，从新生儿到成年，II型mRNA水平相对于IIA型水平下降。使用类似的方法，我们在新生和成年大鼠大脑皮层以及成年大鼠心脏中检测到了编码大鼠心脏钠通道的mRNA。这些结果表明，编码心脏钠通道和所有四种先前测序的大鼠脑钠通道亚型的mRNA在大脑皮层中表达，并且II型和IIA型通道在发育过程中可能受到不同的调节。
