Prazosin and Phentolamine: Comparative Cardiovascular and Autonomic Profiles

α2‐Autoreceptor subclassification in rat isolated kidney by use of short trains of electrical stimulation

“…Prazosin (0.1 ylM) slightly enhanced S-I outflow of radioactivity, but at the same time also enhanced the spontaneous outflow of radioactivity from the tissue. Thus it seems likely, that the slight facilitatory effect of prazosin (1.0 jAM) on S-I outflow of radioactivity was due to an unspecific, possibly reserpine-like (Commarato et al, 1978) effect, reported recently for the rabbit brain cortex in the absence of autoinhibition (Limberger et al, 1991). The increase in perfusion pressure in response to renal nerve stimulation at 100 Hz for 0.06 s was very small.…”

Plasma Noradrenaline Concentration and α-Adrenoceptor-Mediated Vasoconstriction in Normotensive and Hypertensive Man

“…The effect of an intra-arterial infusion of phentolamine on the forearm circulation was then used to assess the er-adrenoceptor-mediated component of vascular resistance. Phentolamine is an a-adrenoceptor antagonist and the vasodilatation after its administration is highly dependent on the presence of an intact sympathetic vascular innervation (Cammarata" Langley, Dugan, Lattima, Smith, Tessman & Kaplan, 1978;Lefevre-Borg, Roach & Cavero, 1978). In addition it may have fJadrenoceptor stimulatory effects (Zahir & Gould, 1971;Drayer, Weber, Atlas & Laragh, 1977).…”

A Pharmacological Analysis of the α-Adrenoceptor Antagonism by Prazosin in Arteries and Veins

“…For example, prazosin results in little tachycardia and virtually no change in plasma renin activity, whereas phentolamine leads to rather substantial increases in both parameters [Massingham and Hayden, 1975]. In addition, prazosin has been shown to produce relatively little orthostatic hypo tension [Stokes and Oates, 1978], an effect which is quite prominent following adminis tration of phentolamine [Commarato et al. 1978], These differences in hemodynamic ef fects between prazosin and phentolamine.…”

“…Constantine et al [1973] found that prazosin produced inconsistent inhibi tion of the vertical tilt-induced pressor re sponse. Commarato et al [1978] reported that although prazosin interfered with the pressor response as a result of vertical tilt in spontaneously hypertensive rats, it did so to a much less extent than did phentolamine.…”