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Effects of losartan on cerebral and ocular circulation in healthy subjects
Author(s) -
Matulla Bettina,
Streit Gabriele,
Pieh Stefan,
Findl Oliver,
Entlicher Jesusa,
Graselli Ursula,
Eichler HansGeorg,
Wolzt Michael,
Schmetterer Leopold
Publication year - 1997
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1046/j.1365-2125.1997.t01-1-00598.x
Subject(s) - losartan , medicine , hemodynamics , ophthalmic artery , angiotensin ii , blood pressure , central retinal artery , cerebral circulation , crossover study , blood flow , anesthesia , placebo , cardiology , pathology , alternative medicine
Aims The introduction of specific inhibitors of AT 1 receptors, such as losartan, has enabled the investigation of the renin‐angiotensin‐system (RAS) in humans in vivo . We studied the role of the RAS in the cerebral and ocular circulation in healthy subjects. Haemodynamic effects of orally administered losartan were investigated with non‐invasive methods. Methods In a placebo‐controlled randomized, double‐blind two way crossover design losartan (100 mg orally) or placebo was administered in 10 healthy subjects. The effect of losartan was studied at hourly intervals for 8 h. In addition, the effect of losartan on haemodynamic changes induced by exogenous angiotensin II (Ang II) was assessed. Blood flow velocities in the ophthalmic and the middle cerebral artery (OA, MCA) were measured with Doppler sonography. Pulsatile choroidal blood flow was estimated with laser interferometric measurement of fundus pulsation. Results Losartan significantly increased fundus pulsation amplitude (+11%, 95% CI: 5 to 16%P <0.0001), tended to increase resistive index in the ophthalmic artery (+12%, 95% CI: 0 to 23%) and tended to decrease mean arterial pressure (−15%, 95% CI: −23 to −1%). Ang II induced effects on cerebral, ocular and systemic haemodynamics were prevented by preceding administration of losartan. Conclusions The present data suggest that Ang II is not a major determinant of cerebral and ocular blood flow in vivo . The observed changes in cerebral and ocular haemodynamic parameters after losartan administration reflect effects on systemic blood pressure.