Effects of postnatal growth and denervation on characteristics of the saphenous artery in SHR and WKY rats between 3 and 6 weeks of age: an in vitro study

Abstract

Thigh vessels of spontaneously hypertensive (SHR) and Wistar–Kyoto (WKY) rats were unilaterally surgically denervated at 10 days of age by femoral nerve section. Denervated and contralateral control segments of saphenous arteries from 3- and 6-week-old rats were mounted in a small vessel myograph for study. Both strains showed growth changes in blood pressure, but there was no significant difference between WKY and SHR. Both strains also had significant growth changes in vessel dimensions and the in vitro measurements suggested that SHR vessels had a thicker wall. Denervation did not affect vessel size. Transmural nerve stimulation indicated loss of innervation due to the surgical procedure. In the denervated vessels, both norepinephrine (NE) and 5-hydroxytryptamine (5-HT) dose response curves were shifted to the left, indicating a postjunctional increase in sensitivity. Maximum tension developed was in the order K+ > 5-HT > NE. In comparing the two strains, vessels from 6-week-old SHR were less sensitive to 5-HT. Relaxation to acetylcholine was significantly decreased in denervated arteries from WKY, whereas in SHR the significant decrease occurred only at 3 weeks. Denervated vessels from both rat strains at 3 weeks showed greater relaxation to β-receptor activation, but not at 6 weeks of age. Therefore, the absence of functional innervation resulted in altered function of the saphenous artery wall.Key words: blood vessel, artery, denervation, smooth muscle, development.