Aritomo Suzuki

RELAXANT EFFECTS OF VASODILATOR PEPTIDES ON ISOLATED BASILAR ARTERIES FROM STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE RATS

1. The relaxant effects of vasodilator peptides were examined in ring preparations of basilar arteries from stroke‐prone spontaneously hypertensive rats (SHRSP) and Wistar‐Kyoto (WKY) rats.

Endothelium-dependent contraction induced by acetylcholine in isolated rat renal arteries

We investigated whether or not acetylcholine elicited an endothelium-dependent contraction and whether an arachidonic acid metabolite was involved in the acetylcholine-induced contraction in ring preparations of rat renal arteries. Acetylcholine (0.1-100 microM) caused a transient contraction in endothelium-intact arteries in a concentration-dependent manner. The contraction induced by acetylcholine (10 microM) was enhanced by pretreatment with NG-nitro-L-arginine (100 microM), a nitric oxide synthase inhibitor, and was abolished by mechanical removal of the endothelium. Atropine (0.1 microM), quinacrine (1 and 3 microM), manoalide (0.1 and 1 microM), aspirin (1 and 10 microM), indomethacin (30 and 300 nM), ONO-3708 (9,11-dimethyl-methane-11,12-methano-13,14-dihydro-13-aza-14- oxo-15(beta)-cyclophenyl-omega-pentenor-thromboxane A2 L-arginine salt) (10 nM), S-1452 (calcium (5Z)-1R,2S,3S,4S-7-[3-phenylsulphonyl-aminobicyclo[2.2.1]hep t-2yl]-5- heptenoate hydrate) (3 nM) and SQ29,548 ([1S- [1 alpha,2 beta(5Z),3 beta,4 alpha]]-7-[3-[[2-[(phenylamino) carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoi++ + c acid) (3 and 10 nM), but not hexamethonium (1 microM), OKY-046 (sodium (E)-3-[4-(1- imidazolylmethyl)phenyl]-2-propenoic acid hydrochloride monohydrate) (100 microM) and CS-518 (sodium 2-(1-imidazolylmethyl)-4,5- dihydrobenzo[b]thiophene-6-carboxylate) (10 microM) significantly attenuated the acetylcholine (10 microM)-induced endothelium-dependent contractions in renal arteries pretreated with NG-nitro-L-arginine. These findings suggest that acetylcholine causes endothelium-dependent contraction by stimulation of muscarinic receptors in rat renal arteries, and that an arachidonic acid metabolite(s) of the cyclooxygenase pathway is involved in this endothelium-dependent contraction.

ENHANCED CONTRACTILE RESPONSES MEDIATED BY DIFFERENT 5-HT RECEPTOR SUBTYPES IN BASILAR ARTERIES, SUPERIOR MESENTERIC ARTERIES AND THORACIC AORTAS FROM STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

1. The contractile effects of 5‐hydroxytryptamine (5‐HT) in isolated ring preparations of basilar arteries (BA), thoracic aortas (TA) and superior mesenteric arteries (SMA) from stroke‐prone spontaneously hypertensive rats (SHRSP) and Wistar‐Kyoto (WKY) rats were investigated pharmacologically.

Placental Na+, K+ activated ATP-ase activity in SHRSP in connection with pregnancy induced hypertension and intra-uterine growth retardation.

1. Placental Na+, K+‐ATPase activities were measured in connection with the active transport of amino acid, intrauterine growth retardation (IUGR) or small for date infants (SFD) in salt‐loaded pregnant SHRSP.

AGE-RELATED CHANGES IN CEREBRAL AND PERIPHERAL MONOAMINE CONTENTS IN STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

1. We examined monoamine contents in various regions of the brain and catecholamine contents in the heart and the adrenal gland of stroke‐prone spontaneously hypertensive rats (SHRSP) and Wistar‐Kyoto (WKY) rats aged 1.5, 3 and 6 months.

CALCITONIN GENE-RELATED PEPTIDE-INDUCED RELAXATION IN ISOLATED SMALL SUPERIOR MESENTERIC ARTERIES FROM ADULT STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

1. The relaxant responses to calcitonin gene‐related peptide (CGRP) of the 3rd order branches of the superior mesenteric arteries (SMA) from 6 month old stroke‐prone spontaneously hypertensive rats (SHRSP) and age‐matched Wistar‐Kyoto (WKY) rats were studied in vitro.

TISSUE VARIATION OF ACUTE HAEMODYNAMIC CHANGES BY NG‐NITRO‐L‐ARGININE IN STROKE‐PRONE SPONTANEOUSLY HYPERTENSIVE AND WISTAR‐KYOTO RATS

1. The acute effects of nitric oxide synthase inhibition on the haemodynamics in stroke‐prone spontaneously hypertensive (SHRSP) and normotensive Wistar‐Kyoto (WKY) rats were investigated using radiolabeled microspheres.

DOPAMINE-INDUCED RELAXATION IN ISOLATED INTRARENAL ARTERIES FROM ADULT STROKE-PRONE SPONTANEOUSLY HYPERTENSIVE RATS

1. The relaxant effects of dopamine (DA) on the intrarenal arteries obtained from 6 month old stroke‐prone spontaneously hypertensive rats (SHRSP) and age‐matched Wistar‐Kyoto (WKY) rats were pharmacologically investigated in vitro.

Haemodynamic effects of NO-synthase inhibitors, NG-monomethyl-L-arginine, NG-nitro-L-arginine and NG-nitro-L-arginine methyl ester, and NO-donor, glyceryl trinitrate, in conscious SHRSP and WKY.

1. The experiments were carried out by an ordinary and a microsphere method in order to clarify the effects of three nitric oxide‐synthase inhibitors and ‐donor on the circulating system between SHRSP and WKY.

CHANGES OF ENDOTHELIAL FUNCTIONS IN THE CORONARY ARTERY AFTER CHRONIC NITROARGININE FEEDING

1. The effects of chronic NG‐nitro‐L‐arginine (LNA) feeding on the endothelial function in isolated coronary arteries from stroke‐prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar‐Kyoto (WKY) rats were studied.