[Formation of disruptions of the internal elastica lamina, spontaneous and BAPN induced, in arteries of stroke-prone spontaneously hypertensive rats].

In the caudal and renal arteries of the male Wistar rat, interruptions in the internal elastic lamina (IEL) form spontaneously with age. beta-aminopropionitrile (BAPN), which is an inhibitor of the enzyme lysyl oxidase implicated in the synthesis of elastin, is able to induce in the young Wistar rat interruptions in the IEL which are morphologically very similar to those which form spontaneously. The spontaneously hypertensive strain (SHR), together with the Stroke-Prone spontaneously hypertensive substrain (SHR-SP) which is susceptible to cerebrovascular accidents early in life, have been selected from the Wistar strain. We have compared the incidence of IEL interruptions in caudal and renal arteries from SHR-SP aged 12 and 23 weeks with that observed in age-matched SHR. In addition, we have studied the effect of BAPN, administered from weaning during two weeks, on the formation of interruptions in the IEL in the caudal artery of SHR-SP, SHR and normotensive Wistar and WKY rats. Interruptions in the IEL were quantified by light microscopy on longitudinal semi-thin sections. Results showed that, in the caudal and renal arteries of SHR-SP, the number of interruptions in the IEL which form spontaneously was greater than in SHR. Moreover, BAPN administered between the age of 3 and 5 weeks led to the premature formation of a higher level of interruptions in the IEL in SHR-SP than in the 3 other strains of rat. The SHR was the strain which developed the least.(ABSTRACT TRUNCATED AT 250 WORDS)