Characterization of agonist-induced vasoconstriction in mouse pulmonary artery

Abstract

In recent years, transgenic mouse models have been developed to examine the underlying cellular and molecular mechanisms of lung disease and pulmonary vascular disease, such as asthma, pulmonary thromboembolic disease, and pulmonary hypertension. However, there has not been systematic characterization of the basic physiological pulmonary vascular reactivity in normal and transgenic mice. This represents an intellectual "gap", since it is important to characterize basic murine pulmonary vascular reactivity in response to various contractile and relaxant factors to which the pulmonary vasculature is exposed under physiological conditions. The present study evaluates excitation-and pharmacomechanical-contraction coupling in pulmonary arteries (PA) isolated from wild-type BALB/c mice. We demonstrate that both pharmacoand electromechanical coupling mechanisms exist in mice PA. These arteries are also reactive to stimulation by ␣ 1-adrenergic agonists, serotonin, endothelin-1, vasopressin, and U-46619 (a thromboxane A 2 analog). We conclude that the basic vascular responsiveness of mouse PA is similar to those observed in PA of other species, including rat, pig, and human, albeit on a different scale and to varying amplitudes. pharmacology; store depletion; excitation-contraction coupling; G protein-coupled receptors MICE, ESPECIALLY TRANSGENIC or knockout variants, are increasingly being used to study disease mechanisms. With respect to pulmonary hypertension, transgenic or knockout mouse models have been developed to evaluate the modulation of pulmonary vasoconstriction and remodeling due to 1) endothelial nitric oxide synthase disruption (18,47,57); 2) vasoactive and mitogenic agonists, such as hypoxia-inducible factors-1␣ (63) and -2␣ (2), calcitonin gene-related peptide (5), serotonin (5-HT) (9,32,34,45), matrix metalloproteinases (67), transforming growth factor-␤ (35), and vasoactive intestinal peptide (51); 3) bone morphogenetic protein receptor type II gene mutations and altered bone morphogenetic protein signaling (19,28,40,62); 4) altered function of ion channels (12) and transporters (49); and 5) altered superoxide production (36,38). Despite these studies, there is still relatively little information regarding the basic characterization of the pulmonary vascular reactivity in normal mice. Nor have the excitationcontraction coupling mechanisms, pharmacological properties of vasoactive response to agonists, been evaluated completely in wild-type mice. This represents an intellectual gap, since it is important to characterize basic murine pulmonary vascular reactivity in response to various contractile and relaxant factors to which the pulmonary vasculature is exposed under physiological conditions. The aim of this study was to characterize pulmonary arterial (PA) excitation-contraction coupling and pharmacological properties of PA using isolated PA rings from mice. METHODS AND MATERIALSIsolation of PA rings. Male 5-to 8-wk-old BALB/c mice were used in this study. Use of mice for the experiments presented in...

p75 neurotrophin receptor regulates agonist-induced pulmonary vasoconstriction

“…Our previous histological data showed that ECs were present in the PA rings after contraction experiments (43). Perfusion of bradykinin, an endothelium-dependent vasodilator, caused a marked relaxation in mouse PA rings contracted by 40 mM K ϩ (43).…”

“…Isometric tension was continuously monitored and acquired using DATAQ software (DATAQ Instruments). Resting passive tension was set at 300 mg (43), and rings were equilibrated for 1 h at resting tension and then challenged three times with 40 mM K ϩ perfusate to obtain a stable contractile response. The optimal resting (or basal) tension (300 mg) was determined by our previous study (43) showing that increasing the basal tension from 100 to 300 mg significantly augmented the 40 mM K ϩ -induced active tension in isolated mouse PA rings.…”

“…Resting passive tension was set at 300 mg (43), and rings were equilibrated for 1 h at resting tension and then challenged three times with 40 mM K ϩ perfusate to obtain a stable contractile response. The optimal resting (or basal) tension (300 mg) was determined by our previous study (43) showing that increasing the basal tension from 100 to 300 mg significantly augmented the 40 mM K ϩ -induced active tension in isolated mouse PA rings. To compare active tensions in different arterial rings, the ability to normalize active tension to vessel weight or length is an important factor in interpreting the results.…”

Chronic hypoxia selectively enhances L- and T-type voltage-dependent Ca2+ channel activity in pulmonary artery by upregulating Cav1.2 and Cav3.2

“…Isometric tension was continuously monitored and acquired using DATAQ software (DATAQ Instruments, Akron, OH). Optimal resting tension for mouse PA and MA preparations has been previously reported to be ϳ300 mg (57,58). Unless indicated otherwise, resting tension was set at 300 mg. All the rings were equilibrated for 1 h at resting tension and then challenged three times with 40 mM K ϩ (40K) perfusate to obtain a stable contractile response (57).…”

“…Optimal resting tension for mouse PA and MA preparations has been previously reported to be ϳ300 mg (57,58). Unless indicated otherwise, resting tension was set at 300 mg. All the rings were equilibrated for 1 h at resting tension and then challenged three times with 40 mM K ϩ (40K) perfusate to obtain a stable contractile response (57). Isolated rings were superfused with modified Krebs solution (MKS; at 37°C) consisting of the following (in mM): 138 NaCl, 1.8 CaCl 2, 4.7 KCl, 1.2 MgSO 4, 1.2 NaH2PO4, 5 HEPES, and 10 glucose (pH 7.4 with NaOH).…”