{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T15:27:43Z","timestamp":1791300463232,"version":"4.1.0"},"reference-count":42,"publisher":"American Physiological Society","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Journal of Applied Physiology"],"published-print":{"date-parts":[[2005,2]]},"abstract":"<jats:p> Acute pulmonary hypertension (PH) may arise with or without an increase in vascular smooth muscle (VSM) tone. Our objective was to determine how VSM activation affects both the conduit (CF) and wall buffering (BF) functions of the pulmonary artery (PA) during acute PH states. PA instantaneous flow, pressure, and diameter of six sheep were recorded during normal pressure (CTL) and different states of acute PH: 1) passively induced by PA mechanical occlusion (PPH); 2) actively induced by intravenous administration of phenylephrine (APH); and 3) a combination of both (APPH). To evaluate the direct effect of VSM activation, isobaric (PPH vs. APH) and isometric (CTL vs. APPH) analyses were performed. We calculated the local BF from the elastic (E<jats:sub>PD<\/jats:sub>) and viscous (\u03b7<jats:sub>PD<\/jats:sub>) indexes as \u03b7<jats:sub>PD<\/jats:sub>\/E<jats:sub>PD<\/jats:sub> and the characteristic impedance (Z<jats:sub>C<\/jats:sub>) from pressure and flow to evaluate CF as 1\/Z<jats:sub>C<\/jats:sub>. We also calculated the absolute and normalized cross-sectional pulsatility (P<jats:sub>CS<\/jats:sub> and NP<jats:sub>CS<\/jats:sub>, respectively), the dynamic compliance (C<jats:sub>DYN<\/jats:sub>), the cross-sectional distensibility (D<jats:sub>CS<\/jats:sub>), and the pressure-strain elastic modulus (E<jats:sub>P<\/jats:sub>). The isobaric analysis showed increase of CF, BF, and \u03b7<jats:sub>PD<\/jats:sub> ( P &lt; 0.01) and decrease of E<jats:sub>PD<\/jats:sub> ( P &lt; 0.05) during APH in respect to PPH (concomitant with isobaric VSM activation-induced vasoconstriction, P &lt; 0.01). The isometric analysis showed increase of E<jats:sub>PD<\/jats:sub> and \u03b7<jats:sub>PD<\/jats:sub> ( P &lt; 0.01), nonsignificant difference in BF (even in the presence of a significant mean PA pressure rise, from 14 (SD 6) to 25 (SD 8) mmHg, P &lt; 0.01), and decrease in CF ( P &lt; 0.01) during APPH respect to CTL. Mechanical occlusions (PPH and APPH) reduced BF ( P &lt; 0.01) and increased E<jats:sub>PD<\/jats:sub> ( P &lt; 0.05) with regard to their previous steady states (CTL and APH). Nonsignificant differences were found in E<jats:sub>PD<\/jats:sub> between PPH and APPH. VSM activation (APH and APPH) increased \u03b7<jats:sub>PD<\/jats:sub> ( P &lt; 0.01) respect to their previous passive states (CTL and PPH), but no significant differences were found within similar levels of VSM activation. In conclusion, VSM plays a relevant role in main pulmonary artery function during acute pulmonary hypertension, because isobaric vasoconstriction induced by VSM activation improves both BF and CF, mainly due to the increase in \u03b7<jats:sub>PD<\/jats:sub> concomitant with the arterial compliance. C<jats:sub>DYN<\/jats:sub> and D<jats:sub>CS<\/jats:sub> were the more pertinent clinical indexes of arterial elasticity. Additionally, the \u03b7<jats:sub>PD<\/jats:sub>-mediated preservation of the BF could be evaluated by the geometric related indexes (P<jats:sub>CS<\/jats:sub> and NP<jats:sub>CS<\/jats:sub>), which appear to be qualitative markers of arterial wall viscosity status. <\/jats:p>","DOI":"10.1152\/japplphysiol.00361.2004","type":"journal-article","created":{"date-parts":[[2004,10,15]],"date-time":"2004-10-15T20:13:59Z","timestamp":1097871239000},"page":"605-613","source":"Crossref","is-referenced-by-count":58,"title":["Pulmonary artery smooth muscle activation attenuates arterial dysfunction during acute pulmonary hypertension"],"prefix":"10.1152","volume":"98","author":[{"given":"Daniel Bia","family":"Santana","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan Gabriel","family":"Barra","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan Carlos","family":"Grignola","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fernando Florencio","family":"Gin\u00e9s","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ricardo Luis","family":"Armentano","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"24","reference":[{"key":"R1","doi-asserted-by":"publisher","DOI":"10.1161\/01.RES.76.3.468"},{"key":"R2","doi-asserted-by":"publisher","DOI":"10.1161\/01.HYP.32.2.356"},{"key":"R3","unstructured":"Barnes PJ and Liu SF. 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