K. Morita et al., EFFECT OF ENDOTHELIUM OF PULMONARY-ARTERY VASOREACTIVITY IN MONOCROTALINE-INDUCED PULMONARY HYPERTENSIVE RATS, Japanese Circulation Journal, 60(8), 1996, pp. 585-592
This study investigated vasoreactivity modulated by endothelium in pul
monary arteries from isolated monocrotaline (MCT)-induced pulmonary hy
pertensive rats. The responses to KCl, 5-hydroxytryptamine (5-HT), ace
tylcholine (ACh), and nitroglycerin (NTG) were studied in the pulmonar
y artery with and without endothelium for 3 weeks following MCT-treatm
ent. The sensitivity of the contractile response to KCl markedly incre
ased in the arteries with endothelium at 2 and 3 weeks after treatment
, but only slightly in the arteries without endothelium. In addition,
the sensitivity of the contractile response to 5-HT peaked 2 weeks aft
er treatment in the arteries with endothelium, but at 1 week in those
without endothelium. Although the removal of endothelium shifted the c
oncentration-response curve for KCl and 5-HT to the left both in the c
ontrol state and at 1 week, it did not shift the curves at 2 or 3 week
s. The relaxation responses to ACh and NTG, indicative of endothelium-
dependent and -independent relaxation, respectively, as well as the co
ntent of tissue cGMP were reduced 2 weeks after treatment. These resul
ts suggest that the impairment of both the endothelium-dependent and -
independent relaxation responses contributes to hyperreactivity of the
pulmonary artery, and may in part contribute to the development of MC
T-induced pulmonary hypertension.